From 7dd4032093ec529f1e0c0eea66dc90e94a60899c Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Tue, 13 Jan 2026 02:51:13 +0000
Subject: [PATCH 1/8] Initial plan


From f0a87f3ad24134e31e63bdbef877b0dc6f9d761d Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Tue, 13 Jan 2026 02:57:21 +0000
Subject: [PATCH 2/8] Add tests for empty response body JSON parsing issue

Co-authored-by: mrlubos <12529395+mrlubos@users.noreply.github.com>
---
 .../src/__tests__/client.test.ts              | 65 ++++++++++++++++++-
 .../client-fetch/__tests__/client.test.ts     | 39 +++++++++++
 .../client-ky/__tests__/client.test.ts        | 39 +++++++++++
 .../client-next/__tests__/client.test.ts      | 63 ++++++++++++++++++
 4 files changed, 205 insertions(+), 1 deletion(-)

diff --git a/packages/custom-client/src/__tests__/client.test.ts b/packages/custom-client/src/__tests__/client.test.ts
index 4419039549..4cb55a620f 100644
--- a/packages/custom-client/src/__tests__/client.test.ts
+++ b/packages/custom-client/src/__tests__/client.test.ts
@@ -1,4 +1,4 @@
-import { describe, expect, it } from 'vitest';
+import { describe, expect, it, vi } from 'vitest';
 
 import { createClient } from '../client';
 
@@ -48,3 +48,66 @@ describe('buildUrl', () => {
     expect(client.buildUrl(options)).toBe(url);
   });
 });
+
+describe('zero-length body handling', () => {
+  const client = createClient({ baseUrl: 'https://example.com' });
+
+  it('returns empty object for zero-length JSON response', async () => {
+    const mockResponse = new Response(null, {
+      headers: {
+        'Content-Length': '0',
+        'Content-Type': 'application/json',
+      },
+      status: 200,
+    });
+
+    const mockFetch = vi.fn().mockResolvedValue(mockResponse);
+
+    const result = await client.request({
+      fetch: mockFetch,
+      method: 'GET',
+      url: '/test',
+    });
+
+    expect(result.data).toEqual({});
+  });
+
+  it('returns empty object for empty JSON response without Content-Length header (status 200)', async () => {
+    // Simulates a server returning an empty body with status 200 and no Content-Length header
+    // This is the scenario described in the issue where response.json() throws
+    const mockResponse = new Response('', {
+      headers: {
+        'Content-Type': 'application/json',
+      },
+      status: 200,
+    });
+
+    const mockFetch = vi.fn().mockResolvedValue(mockResponse);
+
+    const result = await client.request({
+      fetch: mockFetch,
+      method: 'GET',
+      url: '/test',
+    });
+
+    expect(result.data).toEqual({});
+  });
+
+  it('returns empty object for empty response without Content-Length header and no Content-Type (defaults to JSON)', async () => {
+    // Tests the auto-detection behavior when no Content-Type is provided
+    const mockResponse = new Response('', {
+      status: 200,
+    });
+
+    const mockFetch = vi.fn().mockResolvedValue(mockResponse);
+
+    const result = await client.request({
+      fetch: mockFetch,
+      method: 'GET',
+      url: '/test',
+    });
+
+    // When parseAs is 'auto' and no Content-Type header exists, it should handle empty body gracefully
+    expect(result.data).toBeDefined();
+  });
+});
diff --git a/packages/openapi-ts/src/plugins/@hey-api/client-fetch/__tests__/client.test.ts b/packages/openapi-ts/src/plugins/@hey-api/client-fetch/__tests__/client.test.ts
index dd873afffa..1eca46ea20 100644
--- a/packages/openapi-ts/src/plugins/@hey-api/client-fetch/__tests__/client.test.ts
+++ b/packages/openapi-ts/src/plugins/@hey-api/client-fetch/__tests__/client.test.ts
@@ -221,6 +221,45 @@ describe('zero-length body handling', () => {
     expect(result.data).toBeInstanceOf(Blob);
     expect((result.data as Blob).size).toBeGreaterThan(0);
   });
+
+  it('returns empty object for empty JSON response without Content-Length header (status 200)', async () => {
+    // Simulates a server returning an empty body with status 200 and no Content-Length header
+    // This is the scenario described in the issue where response.json() throws
+    const mockResponse = new Response('', {
+      headers: {
+        'Content-Type': 'application/json',
+      },
+      status: 200,
+    });
+
+    const mockFetch: MockFetch = vi.fn().mockResolvedValue(mockResponse);
+
+    const result = await client.request({
+      fetch: mockFetch,
+      method: 'GET',
+      url: '/test',
+    });
+
+    expect(result.data).toEqual({});
+  });
+
+  it('returns empty object for empty response without Content-Length header and no Content-Type (defaults to JSON)', async () => {
+    // Tests the auto-detection behavior when no Content-Type is provided
+    const mockResponse = new Response('', {
+      status: 200,
+    });
+
+    const mockFetch: MockFetch = vi.fn().mockResolvedValue(mockResponse);
+
+    const result = await client.request({
+      fetch: mockFetch,
+      method: 'GET',
+      url: '/test',
+    });
+
+    // When parseAs is 'auto' and no Content-Type header exists, it should handle empty body gracefully
+    expect(result.data).toBeDefined();
+  });
 });
 
 describe('unserialized request body handling', () => {
diff --git a/packages/openapi-ts/src/plugins/@hey-api/client-ky/__tests__/client.test.ts b/packages/openapi-ts/src/plugins/@hey-api/client-ky/__tests__/client.test.ts
index 2da2979b3a..694aecf381 100644
--- a/packages/openapi-ts/src/plugins/@hey-api/client-ky/__tests__/client.test.ts
+++ b/packages/openapi-ts/src/plugins/@hey-api/client-ky/__tests__/client.test.ts
@@ -219,6 +219,45 @@ describe('zero-length body handling', () => {
     expect(result.data).toBeInstanceOf(Blob);
     expect((result.data as Blob).size).toBeGreaterThan(0);
   });
+
+  it('returns empty object for empty JSON response without Content-Length header (status 200)', async () => {
+    // Simulates a server returning an empty body with status 200 and no Content-Length header
+    // This is the scenario described in the issue where response.json() throws
+    const mockResponse = new Response('', {
+      headers: {
+        'Content-Type': 'application/json',
+      },
+      status: 200,
+    });
+
+    const mockKy = vi.fn().mockResolvedValue(mockResponse);
+
+    const result = await client.request({
+      ky: mockKy as Partial<KyInstance> as KyInstance,
+      method: 'GET',
+      url: '/test',
+    });
+
+    expect(result.data).toEqual({});
+  });
+
+  it('returns empty object for empty response without Content-Length header and no Content-Type (defaults to JSON)', async () => {
+    // Tests the auto-detection behavior when no Content-Type is provided
+    const mockResponse = new Response('', {
+      status: 200,
+    });
+
+    const mockKy = vi.fn().mockResolvedValue(mockResponse);
+
+    const result = await client.request({
+      ky: mockKy as Partial<KyInstance> as KyInstance,
+      method: 'GET',
+      url: '/test',
+    });
+
+    // When parseAs is 'auto' and no Content-Type header exists, it should handle empty body gracefully
+    expect(result.data).toBeDefined();
+  });
 });
 
 describe('unserialized request body handling', () => {
diff --git a/packages/openapi-ts/src/plugins/@hey-api/client-next/__tests__/client.test.ts b/packages/openapi-ts/src/plugins/@hey-api/client-next/__tests__/client.test.ts
index 61eb654b2e..dcebc3c3ff 100644
--- a/packages/openapi-ts/src/plugins/@hey-api/client-next/__tests__/client.test.ts
+++ b/packages/openapi-ts/src/plugins/@hey-api/client-next/__tests__/client.test.ts
@@ -54,6 +54,69 @@ describe('buildUrl', () => {
   });
 });
 
+describe('zero-length body handling', () => {
+  const client = createClient({ baseUrl: 'https://example.com' });
+
+  it('returns empty object for zero-length JSON response', async () => {
+    const mockResponse = new Response(null, {
+      headers: {
+        'Content-Length': '0',
+        'Content-Type': 'application/json',
+      },
+      status: 200,
+    });
+
+    const mockFetch: MockFetch = vi.fn().mockResolvedValue(mockResponse);
+
+    const result = await client.request({
+      fetch: mockFetch,
+      method: 'GET',
+      url: '/test',
+    });
+
+    expect(result.data).toEqual({});
+  });
+
+  it('returns empty object for empty JSON response without Content-Length header (status 200)', async () => {
+    // Simulates a server returning an empty body with status 200 and no Content-Length header
+    // This is the scenario described in the issue where response.json() throws
+    const mockResponse = new Response('', {
+      headers: {
+        'Content-Type': 'application/json',
+      },
+      status: 200,
+    });
+
+    const mockFetch: MockFetch = vi.fn().mockResolvedValue(mockResponse);
+
+    const result = await client.request({
+      fetch: mockFetch,
+      method: 'GET',
+      url: '/test',
+    });
+
+    expect(result.data).toEqual({});
+  });
+
+  it('returns empty object for empty response without Content-Length header and no Content-Type (defaults to JSON)', async () => {
+    // Tests the auto-detection behavior when no Content-Type is provided
+    const mockResponse = new Response('', {
+      status: 200,
+    });
+
+    const mockFetch: MockFetch = vi.fn().mockResolvedValue(mockResponse);
+
+    const result = await client.request({
+      fetch: mockFetch,
+      method: 'GET',
+      url: '/test',
+    });
+
+    // When parseAs is 'auto' and no Content-Type header exists, it should handle empty body gracefully
+    expect(result.data).toBeDefined();
+  });
+});
+
 describe('unserialized request body handling', () => {
   const client = createClient({ baseUrl: 'https://example.com' });
 

From b723dba806976d4cae941669f11fca8b49fa0c0f Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Tue, 13 Jan 2026 03:03:08 +0000
Subject: [PATCH 3/8] Fix empty response body JSON parsing to prevent
 'Unexpected end of JSON input' error

Co-authored-by: mrlubos <12529395+mrlubos@users.noreply.github.com>
---
 packages/custom-client/src/client.ts                 | 12 +++++++++++-
 .../plugins/@hey-api/client-fetch/bundle/client.ts   | 12 +++++++++++-
 .../src/plugins/@hey-api/client-ky/bundle/client.ts  | 12 +++++++++++-
 .../plugins/@hey-api/client-next/bundle/client.ts    | 12 +++++++++++-
 4 files changed, 44 insertions(+), 4 deletions(-)

diff --git a/packages/custom-client/src/client.ts b/packages/custom-client/src/client.ts
index 2a5af631ac..bbed43d465 100644
--- a/packages/custom-client/src/client.ts
+++ b/packages/custom-client/src/client.ts
@@ -111,10 +111,20 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; detect empty via clone().text() first.
+          const txt = await response.clone().text();
+          if (!txt) {
+            data = {};
+          } else {
+            data = await response.json();
+          }
+          break;
+        }
         case 'stream':
           return {
             data: response.body,
diff --git a/packages/openapi-ts/src/plugins/@hey-api/client-fetch/bundle/client.ts b/packages/openapi-ts/src/plugins/@hey-api/client-fetch/bundle/client.ts
index dafdbd222f..2985ce78d5 100644
--- a/packages/openapi-ts/src/plugins/@hey-api/client-fetch/bundle/client.ts
+++ b/packages/openapi-ts/src/plugins/@hey-api/client-fetch/bundle/client.ts
@@ -180,10 +180,20 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; detect empty via clone().text() first.
+          const txt = await response.clone().text();
+          if (!txt) {
+            data = {};
+          } else {
+            data = await response.json();
+          }
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts/src/plugins/@hey-api/client-ky/bundle/client.ts b/packages/openapi-ts/src/plugins/@hey-api/client-ky/bundle/client.ts
index 7bfbf95908..5316534559 100644
--- a/packages/openapi-ts/src/plugins/@hey-api/client-ky/bundle/client.ts
+++ b/packages/openapi-ts/src/plugins/@hey-api/client-ky/bundle/client.ts
@@ -249,10 +249,20 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; detect empty via clone().text() first.
+          const txt = await response.clone().text();
+          if (!txt) {
+            data = {};
+          } else {
+            data = await response.json();
+          }
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts/src/plugins/@hey-api/client-next/bundle/client.ts b/packages/openapi-ts/src/plugins/@hey-api/client-next/bundle/client.ts
index 06e2ca5107..5aa4a37745 100644
--- a/packages/openapi-ts/src/plugins/@hey-api/client-next/bundle/client.ts
+++ b/packages/openapi-ts/src/plugins/@hey-api/client-next/bundle/client.ts
@@ -142,10 +142,20 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; detect empty via clone().text() first.
+          const txt = await response.clone().text();
+          if (!txt) {
+            data = {};
+          } else {
+            data = await response.json();
+          }
+          break;
+        }
         case 'stream':
           return {
             data: response.body,

From 7bcbb60ae059f020ed884a25c65b0d7233e9583b Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Tue, 13 Jan 2026 03:25:32 +0000
Subject: [PATCH 4/8] Optimize JSON parsing to avoid reading response body
 twice

Co-authored-by: mrlubos <12529395+mrlubos@users.noreply.github.com>
---
 packages/custom-client/src/client.ts                   | 10 +++-------
 .../src/plugins/@hey-api/client-fetch/bundle/client.ts | 10 +++-------
 .../src/plugins/@hey-api/client-ky/bundle/client.ts    | 10 +++-------
 .../src/plugins/@hey-api/client-next/bundle/client.ts  | 10 +++-------
 4 files changed, 12 insertions(+), 28 deletions(-)

diff --git a/packages/custom-client/src/client.ts b/packages/custom-client/src/client.ts
index bbed43d465..4624d75001 100644
--- a/packages/custom-client/src/client.ts
+++ b/packages/custom-client/src/client.ts
@@ -116,13 +116,9 @@ export const createClient = (config: Config = {}): Client => {
           break;
         case 'json': {
           // Some servers return 200 with no Content-Length and empty body.
-          // response.json() would throw; detect empty via clone().text() first.
-          const txt = await response.clone().text();
-          if (!txt) {
-            data = {};
-          } else {
-            data = await response.json();
-          }
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
           break;
         }
         case 'stream':
diff --git a/packages/openapi-ts/src/plugins/@hey-api/client-fetch/bundle/client.ts b/packages/openapi-ts/src/plugins/@hey-api/client-fetch/bundle/client.ts
index 2985ce78d5..9c41ac870a 100644
--- a/packages/openapi-ts/src/plugins/@hey-api/client-fetch/bundle/client.ts
+++ b/packages/openapi-ts/src/plugins/@hey-api/client-fetch/bundle/client.ts
@@ -185,13 +185,9 @@ export const createClient = (config: Config = {}): Client => {
           break;
         case 'json': {
           // Some servers return 200 with no Content-Length and empty body.
-          // response.json() would throw; detect empty via clone().text() first.
-          const txt = await response.clone().text();
-          if (!txt) {
-            data = {};
-          } else {
-            data = await response.json();
-          }
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
           break;
         }
         case 'stream':
diff --git a/packages/openapi-ts/src/plugins/@hey-api/client-ky/bundle/client.ts b/packages/openapi-ts/src/plugins/@hey-api/client-ky/bundle/client.ts
index 5316534559..35e1b019a0 100644
--- a/packages/openapi-ts/src/plugins/@hey-api/client-ky/bundle/client.ts
+++ b/packages/openapi-ts/src/plugins/@hey-api/client-ky/bundle/client.ts
@@ -254,13 +254,9 @@ export const createClient = (config: Config = {}): Client => {
           break;
         case 'json': {
           // Some servers return 200 with no Content-Length and empty body.
-          // response.json() would throw; detect empty via clone().text() first.
-          const txt = await response.clone().text();
-          if (!txt) {
-            data = {};
-          } else {
-            data = await response.json();
-          }
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
           break;
         }
         case 'stream':
diff --git a/packages/openapi-ts/src/plugins/@hey-api/client-next/bundle/client.ts b/packages/openapi-ts/src/plugins/@hey-api/client-next/bundle/client.ts
index 5aa4a37745..c49ed7b2f6 100644
--- a/packages/openapi-ts/src/plugins/@hey-api/client-next/bundle/client.ts
+++ b/packages/openapi-ts/src/plugins/@hey-api/client-next/bundle/client.ts
@@ -147,13 +147,9 @@ export const createClient = (config: Config = {}): Client => {
           break;
         case 'json': {
           // Some servers return 200 with no Content-Length and empty body.
-          // response.json() would throw; detect empty via clone().text() first.
-          const txt = await response.clone().text();
-          if (!txt) {
-            data = {};
-          } else {
-            data = await response.json();
-          }
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
           break;
         }
         case 'stream':

From d6a80600e40743d41d4f95eb4ead0b9ba42db04b Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Tue, 13 Jan 2026 07:24:46 +0000
Subject: [PATCH 5/8] Update snapshots and examples with optimized JSON parsing

Co-authored-by: mrlubos <12529395+mrlubos@users.noreply.github.com>
---
 .../openapi-ts-fastify/src/client/client/client.gen.ts    | 8 +++++++-
 examples/openapi-ts-fetch/src/client/client/client.gen.ts | 8 +++++++-
 examples/openapi-ts-ky/src/client/client/client.gen.ts    | 8 +++++++-
 examples/openapi-ts-next/src/client/client/client.gen.ts  | 8 +++++++-
 .../openapi-ts-openai/src/client/client/client.gen.ts     | 8 +++++++-
 .../src/client/client/client.gen.ts                       | 8 +++++++-
 .../src/client/client/client.gen.ts                       | 8 +++++++-
 .../src/client/client/client.gen.ts                       | 8 +++++++-
 .../src/client/client/client.gen.ts                       | 8 +++++++-
 .../plugins/@tanstack/meta/client/client.gen.ts           | 8 +++++++-
 .../2.0.x/body-response-text-plain/client/client.gen.ts   | 8 +++++++-
 .../__snapshots__/2.0.x/form-data/client/client.gen.ts    | 8 +++++++-
 .../sdk-nested-classes-instance/client/client.gen.ts      | 8 +++++++-
 .../client-fetch/sdk-nested-classes/client/client.gen.ts  | 8 +++++++-
 .../plugins/@hey-api/sdk/default/client/client.gen.ts     | 8 +++++++-
 .../plugins/@hey-api/sdk/instance/client/client.gen.ts    | 8 +++++++-
 .../@hey-api/sdk/throwOnError/client/client.gen.ts        | 8 +++++++-
 .../transformers/type-format-valibot/client/client.gen.ts | 8 +++++++-
 .../transformers/type-format-zod/client/client.gen.ts     | 8 +++++++-
 .../client/client.gen.ts                                  | 8 +++++++-
 .../transforms-read-write-ignore/client/client.gen.ts     | 8 +++++++-
 .../plugins/@pinia/colada/asClass/client/client.gen.ts    | 8 +++++++-
 .../plugins/@pinia/colada/fetch/client/client.gen.ts      | 8 +++++++-
 .../asClass/client/client.gen.ts                          | 8 +++++++-
 .../angular-query-experimental/fetch/client/client.gen.ts | 8 +++++++-
 .../name-builder/client/client.gen.ts                     | 8 +++++++-
 .../@tanstack/react-query/asClass/client/client.gen.ts    | 8 +++++++-
 .../@tanstack/react-query/fetch/client/client.gen.ts      | 8 +++++++-
 .../react-query/name-builder/client/client.gen.ts         | 8 +++++++-
 .../@tanstack/solid-query/asClass/client/client.gen.ts    | 8 +++++++-
 .../@tanstack/solid-query/fetch/client/client.gen.ts      | 8 +++++++-
 .../solid-query/name-builder/client/client.gen.ts         | 8 +++++++-
 .../@tanstack/svelte-query/asClass/client/client.gen.ts   | 8 +++++++-
 .../@tanstack/svelte-query/fetch/client/client.gen.ts     | 8 +++++++-
 .../svelte-query/name-builder/client/client.gen.ts        | 8 +++++++-
 .../@tanstack/vue-query/asClass/client/client.gen.ts      | 8 +++++++-
 .../@tanstack/vue-query/fetch/client/client.gen.ts        | 8 +++++++-
 .../@tanstack/vue-query/name-builder/client/client.gen.ts | 8 +++++++-
 .../2.0.x/schema-unknown/client/client.gen.ts             | 8 +++++++-
 .../2.0.x/security-api-key/client/client.gen.ts           | 8 +++++++-
 .../2.0.x/security-basic/client/client.gen.ts             | 8 +++++++-
 .../2.0.x/security-false/client/client.gen.ts             | 8 +++++++-
 .../2.0.x/security-oauth2/client/client.gen.ts            | 8 +++++++-
 .../2.0.x/servers-base-path/client/client.gen.ts          | 8 +++++++-
 .../__snapshots__/2.0.x/servers-host/client/client.gen.ts | 8 +++++++-
 .../test/__snapshots__/2.0.x/servers/client/client.gen.ts | 8 +++++++-
 .../2.0.x/transforms-read-write/client/client.gen.ts      | 8 +++++++-
 .../3.0.x/body-binary-format/client/client.gen.ts         | 8 +++++++-
 .../3.0.x/body-response-text-plain/client/client.gen.ts   | 8 +++++++-
 .../3.0.x/internal-name-conflict/client/client.gen.ts     | 8 +++++++-
 .../3.0.x/parameter-explode-false/client/client.gen.ts    | 8 +++++++-
 .../sdk-nested-classes-instance/client/client.gen.ts      | 8 +++++++-
 .../client-fetch/sdk-nested-classes/client/client.gen.ts  | 8 +++++++-
 .../plugins/@hey-api/sdk/default/client/client.gen.ts     | 8 +++++++-
 .../plugins/@hey-api/sdk/instance/client/client.gen.ts    | 8 +++++++-
 .../@hey-api/sdk/throwOnError/client/client.gen.ts        | 8 +++++++-
 .../transformers/type-format-valibot/client/client.gen.ts | 8 +++++++-
 .../transformers/type-format-zod/client/client.gen.ts     | 8 +++++++-
 .../client/client.gen.ts                                  | 8 +++++++-
 .../transforms-read-write-ignore/client/client.gen.ts     | 8 +++++++-
 .../plugins/@pinia/colada/asClass/client/client.gen.ts    | 8 +++++++-
 .../plugins/@pinia/colada/fetch/client/client.gen.ts      | 8 +++++++-
 .../asClass/client/client.gen.ts                          | 8 +++++++-
 .../angular-query-experimental/fetch/client/client.gen.ts | 8 +++++++-
 .../name-builder/client/client.gen.ts                     | 8 +++++++-
 .../@tanstack/react-query/asClass/client/client.gen.ts    | 8 +++++++-
 .../@tanstack/react-query/fetch/client/client.gen.ts      | 8 +++++++-
 .../react-query/name-builder/client/client.gen.ts         | 8 +++++++-
 .../@tanstack/solid-query/asClass/client/client.gen.ts    | 8 +++++++-
 .../@tanstack/solid-query/fetch/client/client.gen.ts      | 8 +++++++-
 .../solid-query/name-builder/client/client.gen.ts         | 8 +++++++-
 .../@tanstack/svelte-query/asClass/client/client.gen.ts   | 8 +++++++-
 .../@tanstack/svelte-query/fetch/client/client.gen.ts     | 8 +++++++-
 .../svelte-query/name-builder/client/client.gen.ts        | 8 +++++++-
 .../@tanstack/vue-query/asClass/client/client.gen.ts      | 8 +++++++-
 .../@tanstack/vue-query/fetch/client/client.gen.ts        | 8 +++++++-
 .../@tanstack/vue-query/name-builder/client/client.gen.ts | 8 +++++++-
 .../3.0.x/security-api-key/client/client.gen.ts           | 8 +++++++-
 .../3.0.x/security-false/client/client.gen.ts             | 8 +++++++-
 .../3.0.x/security-http-bearer/client/client.gen.ts       | 8 +++++++-
 .../3.0.x/security-oauth2/client/client.gen.ts            | 8 +++++++-
 .../3.0.x/security-open-id-connect/client/client.gen.ts   | 8 +++++++-
 .../test/__snapshots__/3.0.x/servers/client/client.gen.ts | 8 +++++++-
 .../3.0.x/transformers-all-of/client/client.gen.ts        | 8 +++++++-
 .../3.0.x/transformers-any-of-null/client/client.gen.ts   | 8 +++++++-
 .../3.0.x/transformers-array/client/client.gen.ts         | 8 +++++++-
 .../3.0.x/transformers-recursive/client/client.gen.ts     | 8 +++++++-
 .../3.0.x/transforms-read-write/client/client.gen.ts      | 8 +++++++-
 .../3.1.x/body-response-text-plain/client/client.gen.ts   | 8 +++++++-
 .../client-fetch/base-url-false/client/client.gen.ts      | 8 +++++++-
 .../client-fetch/base-url-number/client/client.gen.ts     | 8 +++++++-
 .../client-fetch/base-url-strict/client/client.gen.ts     | 8 +++++++-
 .../client-fetch/base-url-string/client/client.gen.ts     | 8 +++++++-
 .../client-fetch/clean-false/client/client.gen.ts         | 8 +++++++-
 .../@hey-api/client-fetch/default/client/client.gen.ts    | 8 +++++++-
 .../import-file-extension-ts/client/client.gen.ts         | 8 +++++++-
 .../client-fetch/sdk-client-optional/client/client.gen.ts | 8 +++++++-
 .../client-fetch/sdk-client-required/client/client.gen.ts | 8 +++++++-
 .../client-fetch/tsconfig-node16-sdk/client/client.gen.ts | 8 +++++++-
 .../tsconfig-nodenext-sdk/client/client.gen.ts            | 8 +++++++-
 .../client-ky/base-url-false/client/client.gen.ts         | 8 +++++++-
 .../client-ky/base-url-number/client/client.gen.ts        | 8 +++++++-
 .../client-ky/base-url-strict/client/client.gen.ts        | 8 +++++++-
 .../client-ky/base-url-string/client/client.gen.ts        | 8 +++++++-
 .../@hey-api/client-ky/clean-false/client/client.gen.ts   | 8 +++++++-
 .../@hey-api/client-ky/default/client/client.gen.ts       | 8 +++++++-
 .../import-file-extension-ts/client/client.gen.ts         | 8 +++++++-
 .../client-ky/sdk-client-optional/client/client.gen.ts    | 8 +++++++-
 .../client-ky/sdk-client-required/client/client.gen.ts    | 8 +++++++-
 .../client-ky/tsconfig-node16-sdk/client/client.gen.ts    | 8 +++++++-
 .../client-ky/tsconfig-nodenext-sdk/client/client.gen.ts  | 8 +++++++-
 .../client-next/base-url-false/client/client.gen.ts       | 8 +++++++-
 .../client-next/base-url-number/client/client.gen.ts      | 8 +++++++-
 .../client-next/base-url-strict/client/client.gen.ts      | 8 +++++++-
 .../client-next/base-url-string/client/client.gen.ts      | 8 +++++++-
 .../@hey-api/client-next/clean-false/client/client.gen.ts | 8 +++++++-
 .../@hey-api/client-next/default/client/client.gen.ts     | 8 +++++++-
 .../import-file-extension-ts/client/client.gen.ts         | 8 +++++++-
 .../client-next/sdk-client-optional/client/client.gen.ts  | 8 +++++++-
 .../client-next/sdk-client-required/client/client.gen.ts  | 8 +++++++-
 .../client-next/tsconfig-node16-sdk/client/client.gen.ts  | 8 +++++++-
 .../tsconfig-nodenext-sdk/client/client.gen.ts            | 8 +++++++-
 .../3.1.x/clients/client-custom/bundle/client/index.cjs   | 6 +++++-
 .../test/__snapshots__/3.1.x/headers/client/client.gen.ts | 8 +++++++-
 .../3.1.x/internal-name-conflict/client/client.gen.ts     | 8 +++++++-
 .../3.1.x/pagination-ref/client/client.gen.ts             | 8 +++++++-
 .../3.1.x/parameter-explode-false/client/client.gen.ts    | 8 +++++++-
 .../sdk-nested-classes-instance/client/client.gen.ts      | 8 +++++++-
 .../client-fetch/sdk-nested-classes/client/client.gen.ts  | 8 +++++++-
 .../plugins/@hey-api/sdk/default/client/client.gen.ts     | 8 +++++++-
 .../plugins/@hey-api/sdk/instance/client/client.gen.ts    | 8 +++++++-
 .../@hey-api/sdk/throwOnError/client/client.gen.ts        | 8 +++++++-
 .../transformers/type-format-valibot/client/client.gen.ts | 8 +++++++-
 .../transformers/type-format-zod/client/client.gen.ts     | 8 +++++++-
 .../client/client.gen.ts                                  | 8 +++++++-
 .../transforms-read-write-ignore/client/client.gen.ts     | 8 +++++++-
 .../plugins/@pinia/colada/asClass/client/client.gen.ts    | 8 +++++++-
 .../plugins/@pinia/colada/fetch/client/client.gen.ts      | 8 +++++++-
 .../asClass/client/client.gen.ts                          | 8 +++++++-
 .../angular-query-experimental/fetch/client/client.gen.ts | 8 +++++++-
 .../name-builder/client/client.gen.ts                     | 8 +++++++-
 .../@tanstack/react-query/asClass/client/client.gen.ts    | 8 +++++++-
 .../@tanstack/react-query/fetch/client/client.gen.ts      | 8 +++++++-
 .../react-query/name-builder/client/client.gen.ts         | 8 +++++++-
 .../@tanstack/solid-query/asClass/client/client.gen.ts    | 8 +++++++-
 .../@tanstack/solid-query/fetch/client/client.gen.ts      | 8 +++++++-
 .../solid-query/name-builder/client/client.gen.ts         | 8 +++++++-
 .../@tanstack/svelte-query/asClass/client/client.gen.ts   | 8 +++++++-
 .../@tanstack/svelte-query/fetch/client/client.gen.ts     | 8 +++++++-
 .../svelte-query/name-builder/client/client.gen.ts        | 8 +++++++-
 .../@tanstack/vue-query/asClass/client/client.gen.ts      | 8 +++++++-
 .../@tanstack/vue-query/fetch/client/client.gen.ts        | 8 +++++++-
 .../@tanstack/vue-query/name-builder/client/client.gen.ts | 8 +++++++-
 .../3.1.x/security-api-key/client/client.gen.ts           | 8 +++++++-
 .../3.1.x/security-false/client/client.gen.ts             | 8 +++++++-
 .../3.1.x/security-http-bearer/client/client.gen.ts       | 8 +++++++-
 .../3.1.x/security-oauth2/client/client.gen.ts            | 8 +++++++-
 .../3.1.x/security-open-id-connect/client/client.gen.ts   | 8 +++++++-
 .../test/__snapshots__/3.1.x/servers/client/client.gen.ts | 8 +++++++-
 .../__snapshots__/3.1.x/sse-fetch/client/client.gen.ts    | 8 +++++++-
 .../__snapshots__/3.1.x/sse-next/client/client.gen.ts     | 8 +++++++-
 .../3.1.x/transformers-all-of/client/client.gen.ts        | 8 +++++++-
 .../3.1.x/transformers-any-of-null/client/client.gen.ts   | 8 +++++++-
 .../3.1.x/transformers-array/client/client.gen.ts         | 8 +++++++-
 .../3.1.x/transformers-recursive/client/client.gen.ts     | 8 +++++++-
 .../3.1.x/transforms-read-write/client/client.gen.ts      | 8 +++++++-
 .../method-class-conflict/class/client/client.gen.ts      | 8 +++++++-
 .../method-class-conflict/flat/client/client.gen.ts       | 8 +++++++-
 .../method-class-conflict/instance/client/client.gen.ts   | 8 +++++++-
 .../opencode/export-all/client/client.gen.ts              | 8 +++++++-
 .../sdks/__snapshots__/opencode/flat/client/client.gen.ts | 8 +++++++-
 .../__snapshots__/opencode/grouped/client/client.gen.ts   | 8 +++++++-
 172 files changed, 1202 insertions(+), 172 deletions(-)

diff --git a/examples/openapi-ts-fastify/src/client/client/client.gen.ts b/examples/openapi-ts-fastify/src/client/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/examples/openapi-ts-fastify/src/client/client/client.gen.ts
+++ b/examples/openapi-ts-fastify/src/client/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/examples/openapi-ts-fetch/src/client/client/client.gen.ts b/examples/openapi-ts-fetch/src/client/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/examples/openapi-ts-fetch/src/client/client/client.gen.ts
+++ b/examples/openapi-ts-fetch/src/client/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/examples/openapi-ts-ky/src/client/client/client.gen.ts b/examples/openapi-ts-ky/src/client/client/client.gen.ts
index 27da91a539..005420333b 100644
--- a/examples/openapi-ts-ky/src/client/client/client.gen.ts
+++ b/examples/openapi-ts-ky/src/client/client/client.gen.ts
@@ -251,10 +251,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/examples/openapi-ts-next/src/client/client/client.gen.ts b/examples/openapi-ts-next/src/client/client/client.gen.ts
index f87d22dab4..7ad3017a86 100644
--- a/examples/openapi-ts-next/src/client/client/client.gen.ts
+++ b/examples/openapi-ts-next/src/client/client/client.gen.ts
@@ -144,10 +144,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return {
             data: response.body,
diff --git a/examples/openapi-ts-openai/src/client/client/client.gen.ts b/examples/openapi-ts-openai/src/client/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/examples/openapi-ts-openai/src/client/client/client.gen.ts
+++ b/examples/openapi-ts-openai/src/client/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/examples/openapi-ts-pinia-colada/src/client/client/client.gen.ts b/examples/openapi-ts-pinia-colada/src/client/client/client.gen.ts
index b8e7d6afd7..3b6add19f7 100644
--- a/examples/openapi-ts-pinia-colada/src/client/client/client.gen.ts
+++ b/examples/openapi-ts-pinia-colada/src/client/client/client.gen.ts
@@ -164,10 +164,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]()
           break
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text()
+          data = text ? JSON.parse(text) : {}
+          break
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/examples/openapi-ts-tanstack-react-query/src/client/client/client.gen.ts b/examples/openapi-ts-tanstack-react-query/src/client/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/examples/openapi-ts-tanstack-react-query/src/client/client/client.gen.ts
+++ b/examples/openapi-ts-tanstack-react-query/src/client/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/examples/openapi-ts-tanstack-svelte-query/src/client/client/client.gen.ts b/examples/openapi-ts-tanstack-svelte-query/src/client/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/examples/openapi-ts-tanstack-svelte-query/src/client/client/client.gen.ts
+++ b/examples/openapi-ts-tanstack-svelte-query/src/client/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/examples/openapi-ts-tanstack-vue-query/src/client/client/client.gen.ts b/examples/openapi-ts-tanstack-vue-query/src/client/client/client.gen.ts
index b8e7d6afd7..3b6add19f7 100644
--- a/examples/openapi-ts-tanstack-vue-query/src/client/client/client.gen.ts
+++ b/examples/openapi-ts-tanstack-vue-query/src/client/client/client.gen.ts
@@ -164,10 +164,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]()
           break
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text()
+          data = text ? JSON.parse(text) : {}
+          break
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/__snapshots__/plugins/@tanstack/meta/client/client.gen.ts b/packages/openapi-ts-tests/__snapshots__/plugins/@tanstack/meta/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/__snapshots__/plugins/@tanstack/meta/client/client.gen.ts
+++ b/packages/openapi-ts-tests/__snapshots__/plugins/@tanstack/meta/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/body-response-text-plain/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/body-response-text-plain/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/body-response-text-plain/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/body-response-text-plain/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/form-data/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/form-data/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/form-data/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/form-data/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@hey-api/client-fetch/sdk-nested-classes-instance/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@hey-api/client-fetch/sdk-nested-classes-instance/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@hey-api/client-fetch/sdk-nested-classes-instance/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@hey-api/client-fetch/sdk-nested-classes-instance/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@hey-api/client-fetch/sdk-nested-classes/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@hey-api/client-fetch/sdk-nested-classes/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@hey-api/client-fetch/sdk-nested-classes/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@hey-api/client-fetch/sdk-nested-classes/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@hey-api/sdk/default/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@hey-api/sdk/default/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@hey-api/sdk/default/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@hey-api/sdk/default/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@hey-api/sdk/instance/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@hey-api/sdk/instance/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@hey-api/sdk/instance/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@hey-api/sdk/instance/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@hey-api/sdk/throwOnError/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@hey-api/sdk/throwOnError/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@hey-api/sdk/throwOnError/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@hey-api/sdk/throwOnError/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@hey-api/transformers/type-format-valibot/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@hey-api/transformers/type-format-valibot/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@hey-api/transformers/type-format-valibot/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@hey-api/transformers/type-format-valibot/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@hey-api/transformers/type-format-zod/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@hey-api/transformers/type-format-zod/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@hey-api/transformers/type-format-zod/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@hey-api/transformers/type-format-zod/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@hey-api/typescript/transforms-read-write-custom-name/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@hey-api/typescript/transforms-read-write-custom-name/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@hey-api/typescript/transforms-read-write-custom-name/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@hey-api/typescript/transforms-read-write-custom-name/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@hey-api/typescript/transforms-read-write-ignore/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@hey-api/typescript/transforms-read-write-ignore/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@hey-api/typescript/transforms-read-write-ignore/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@hey-api/typescript/transforms-read-write-ignore/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@pinia/colada/asClass/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@pinia/colada/asClass/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@pinia/colada/asClass/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@pinia/colada/asClass/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@pinia/colada/fetch/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@pinia/colada/fetch/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@pinia/colada/fetch/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@pinia/colada/fetch/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@tanstack/angular-query-experimental/asClass/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@tanstack/angular-query-experimental/asClass/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@tanstack/angular-query-experimental/asClass/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@tanstack/angular-query-experimental/asClass/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@tanstack/angular-query-experimental/fetch/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@tanstack/angular-query-experimental/fetch/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@tanstack/angular-query-experimental/fetch/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@tanstack/angular-query-experimental/fetch/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@tanstack/angular-query-experimental/name-builder/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@tanstack/angular-query-experimental/name-builder/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@tanstack/angular-query-experimental/name-builder/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@tanstack/angular-query-experimental/name-builder/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@tanstack/react-query/asClass/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@tanstack/react-query/asClass/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@tanstack/react-query/asClass/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@tanstack/react-query/asClass/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@tanstack/react-query/fetch/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@tanstack/react-query/fetch/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@tanstack/react-query/fetch/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@tanstack/react-query/fetch/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@tanstack/react-query/name-builder/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@tanstack/react-query/name-builder/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@tanstack/react-query/name-builder/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@tanstack/react-query/name-builder/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@tanstack/solid-query/asClass/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@tanstack/solid-query/asClass/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@tanstack/solid-query/asClass/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@tanstack/solid-query/asClass/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@tanstack/solid-query/fetch/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@tanstack/solid-query/fetch/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@tanstack/solid-query/fetch/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@tanstack/solid-query/fetch/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@tanstack/solid-query/name-builder/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@tanstack/solid-query/name-builder/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@tanstack/solid-query/name-builder/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@tanstack/solid-query/name-builder/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@tanstack/svelte-query/asClass/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@tanstack/svelte-query/asClass/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@tanstack/svelte-query/asClass/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@tanstack/svelte-query/asClass/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@tanstack/svelte-query/fetch/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@tanstack/svelte-query/fetch/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@tanstack/svelte-query/fetch/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@tanstack/svelte-query/fetch/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@tanstack/svelte-query/name-builder/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@tanstack/svelte-query/name-builder/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@tanstack/svelte-query/name-builder/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@tanstack/svelte-query/name-builder/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@tanstack/vue-query/asClass/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@tanstack/vue-query/asClass/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@tanstack/vue-query/asClass/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@tanstack/vue-query/asClass/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@tanstack/vue-query/fetch/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@tanstack/vue-query/fetch/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@tanstack/vue-query/fetch/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@tanstack/vue-query/fetch/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@tanstack/vue-query/name-builder/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@tanstack/vue-query/name-builder/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@tanstack/vue-query/name-builder/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/plugins/@tanstack/vue-query/name-builder/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/schema-unknown/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/schema-unknown/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/schema-unknown/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/schema-unknown/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/security-api-key/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/security-api-key/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/security-api-key/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/security-api-key/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/security-basic/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/security-basic/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/security-basic/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/security-basic/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/security-false/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/security-false/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/security-false/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/security-false/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/security-oauth2/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/security-oauth2/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/security-oauth2/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/security-oauth2/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/servers-base-path/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/servers-base-path/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/servers-base-path/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/servers-base-path/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/servers-host/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/servers-host/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/servers-host/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/servers-host/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/servers/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/servers/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/servers/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/servers/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/transforms-read-write/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/transforms-read-write/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/transforms-read-write/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/2.0.x/transforms-read-write/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/body-binary-format/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/body-binary-format/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/body-binary-format/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/body-binary-format/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/body-response-text-plain/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/body-response-text-plain/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/body-response-text-plain/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/body-response-text-plain/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/internal-name-conflict/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/internal-name-conflict/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/internal-name-conflict/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/internal-name-conflict/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/parameter-explode-false/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/parameter-explode-false/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/parameter-explode-false/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/parameter-explode-false/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@hey-api/client-fetch/sdk-nested-classes-instance/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@hey-api/client-fetch/sdk-nested-classes-instance/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@hey-api/client-fetch/sdk-nested-classes-instance/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@hey-api/client-fetch/sdk-nested-classes-instance/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@hey-api/client-fetch/sdk-nested-classes/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@hey-api/client-fetch/sdk-nested-classes/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@hey-api/client-fetch/sdk-nested-classes/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@hey-api/client-fetch/sdk-nested-classes/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@hey-api/sdk/default/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@hey-api/sdk/default/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@hey-api/sdk/default/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@hey-api/sdk/default/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@hey-api/sdk/instance/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@hey-api/sdk/instance/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@hey-api/sdk/instance/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@hey-api/sdk/instance/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@hey-api/sdk/throwOnError/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@hey-api/sdk/throwOnError/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@hey-api/sdk/throwOnError/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@hey-api/sdk/throwOnError/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@hey-api/transformers/type-format-valibot/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@hey-api/transformers/type-format-valibot/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@hey-api/transformers/type-format-valibot/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@hey-api/transformers/type-format-valibot/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@hey-api/transformers/type-format-zod/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@hey-api/transformers/type-format-zod/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@hey-api/transformers/type-format-zod/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@hey-api/transformers/type-format-zod/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@hey-api/typescript/transforms-read-write-custom-name/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@hey-api/typescript/transforms-read-write-custom-name/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@hey-api/typescript/transforms-read-write-custom-name/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@hey-api/typescript/transforms-read-write-custom-name/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@hey-api/typescript/transforms-read-write-ignore/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@hey-api/typescript/transforms-read-write-ignore/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@hey-api/typescript/transforms-read-write-ignore/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@hey-api/typescript/transforms-read-write-ignore/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@pinia/colada/asClass/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@pinia/colada/asClass/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@pinia/colada/asClass/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@pinia/colada/asClass/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@pinia/colada/fetch/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@pinia/colada/fetch/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@pinia/colada/fetch/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@pinia/colada/fetch/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@tanstack/angular-query-experimental/asClass/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@tanstack/angular-query-experimental/asClass/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@tanstack/angular-query-experimental/asClass/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@tanstack/angular-query-experimental/asClass/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@tanstack/angular-query-experimental/fetch/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@tanstack/angular-query-experimental/fetch/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@tanstack/angular-query-experimental/fetch/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@tanstack/angular-query-experimental/fetch/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@tanstack/angular-query-experimental/name-builder/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@tanstack/angular-query-experimental/name-builder/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@tanstack/angular-query-experimental/name-builder/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@tanstack/angular-query-experimental/name-builder/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@tanstack/react-query/asClass/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@tanstack/react-query/asClass/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@tanstack/react-query/asClass/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@tanstack/react-query/asClass/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@tanstack/react-query/fetch/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@tanstack/react-query/fetch/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@tanstack/react-query/fetch/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@tanstack/react-query/fetch/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@tanstack/react-query/name-builder/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@tanstack/react-query/name-builder/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@tanstack/react-query/name-builder/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@tanstack/react-query/name-builder/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@tanstack/solid-query/asClass/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@tanstack/solid-query/asClass/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@tanstack/solid-query/asClass/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@tanstack/solid-query/asClass/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@tanstack/solid-query/fetch/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@tanstack/solid-query/fetch/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@tanstack/solid-query/fetch/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@tanstack/solid-query/fetch/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@tanstack/solid-query/name-builder/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@tanstack/solid-query/name-builder/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@tanstack/solid-query/name-builder/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@tanstack/solid-query/name-builder/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@tanstack/svelte-query/asClass/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@tanstack/svelte-query/asClass/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@tanstack/svelte-query/asClass/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@tanstack/svelte-query/asClass/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@tanstack/svelte-query/fetch/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@tanstack/svelte-query/fetch/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@tanstack/svelte-query/fetch/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@tanstack/svelte-query/fetch/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@tanstack/svelte-query/name-builder/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@tanstack/svelte-query/name-builder/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@tanstack/svelte-query/name-builder/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@tanstack/svelte-query/name-builder/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@tanstack/vue-query/asClass/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@tanstack/vue-query/asClass/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@tanstack/vue-query/asClass/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@tanstack/vue-query/asClass/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@tanstack/vue-query/fetch/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@tanstack/vue-query/fetch/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@tanstack/vue-query/fetch/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@tanstack/vue-query/fetch/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@tanstack/vue-query/name-builder/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@tanstack/vue-query/name-builder/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@tanstack/vue-query/name-builder/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/plugins/@tanstack/vue-query/name-builder/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/security-api-key/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/security-api-key/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/security-api-key/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/security-api-key/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/security-false/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/security-false/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/security-false/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/security-false/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/security-http-bearer/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/security-http-bearer/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/security-http-bearer/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/security-http-bearer/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/security-oauth2/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/security-oauth2/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/security-oauth2/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/security-oauth2/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/security-open-id-connect/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/security-open-id-connect/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/security-open-id-connect/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/security-open-id-connect/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/servers/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/servers/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/servers/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/servers/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/transformers-all-of/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/transformers-all-of/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/transformers-all-of/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/transformers-all-of/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/transformers-any-of-null/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/transformers-any-of-null/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/transformers-any-of-null/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/transformers-any-of-null/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/transformers-array/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/transformers-array/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/transformers-array/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/transformers-array/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/transformers-recursive/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/transformers-recursive/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/transformers-recursive/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/transformers-recursive/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/transforms-read-write/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/transforms-read-write/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/transforms-read-write/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.0.x/transforms-read-write/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/body-response-text-plain/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/body-response-text-plain/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/body-response-text-plain/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/body-response-text-plain/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-fetch/base-url-false/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-fetch/base-url-false/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-fetch/base-url-false/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-fetch/base-url-false/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-fetch/base-url-number/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-fetch/base-url-number/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-fetch/base-url-number/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-fetch/base-url-number/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-fetch/base-url-strict/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-fetch/base-url-strict/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-fetch/base-url-strict/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-fetch/base-url-strict/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-fetch/base-url-string/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-fetch/base-url-string/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-fetch/base-url-string/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-fetch/base-url-string/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-fetch/clean-false/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-fetch/clean-false/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-fetch/clean-false/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-fetch/clean-false/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-fetch/default/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-fetch/default/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-fetch/default/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-fetch/default/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-fetch/import-file-extension-ts/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-fetch/import-file-extension-ts/client/client.gen.ts
index e9e5ac5f78..9f60d8ae04 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-fetch/import-file-extension-ts/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-fetch/import-file-extension-ts/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-fetch/sdk-client-optional/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-fetch/sdk-client-optional/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-fetch/sdk-client-optional/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-fetch/sdk-client-optional/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-fetch/sdk-client-required/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-fetch/sdk-client-required/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-fetch/sdk-client-required/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-fetch/sdk-client-required/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-fetch/tsconfig-node16-sdk/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-fetch/tsconfig-node16-sdk/client/client.gen.ts
index 916301e46a..8eea2b6373 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-fetch/tsconfig-node16-sdk/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-fetch/tsconfig-node16-sdk/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-fetch/tsconfig-nodenext-sdk/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-fetch/tsconfig-nodenext-sdk/client/client.gen.ts
index 916301e46a..8eea2b6373 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-fetch/tsconfig-nodenext-sdk/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-fetch/tsconfig-nodenext-sdk/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-ky/base-url-false/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-ky/base-url-false/client/client.gen.ts
index 27da91a539..005420333b 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-ky/base-url-false/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-ky/base-url-false/client/client.gen.ts
@@ -251,10 +251,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-ky/base-url-number/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-ky/base-url-number/client/client.gen.ts
index 27da91a539..005420333b 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-ky/base-url-number/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-ky/base-url-number/client/client.gen.ts
@@ -251,10 +251,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-ky/base-url-strict/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-ky/base-url-strict/client/client.gen.ts
index 27da91a539..005420333b 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-ky/base-url-strict/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-ky/base-url-strict/client/client.gen.ts
@@ -251,10 +251,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-ky/base-url-string/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-ky/base-url-string/client/client.gen.ts
index 27da91a539..005420333b 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-ky/base-url-string/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-ky/base-url-string/client/client.gen.ts
@@ -251,10 +251,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-ky/clean-false/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-ky/clean-false/client/client.gen.ts
index 27da91a539..005420333b 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-ky/clean-false/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-ky/clean-false/client/client.gen.ts
@@ -251,10 +251,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-ky/default/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-ky/default/client/client.gen.ts
index 27da91a539..005420333b 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-ky/default/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-ky/default/client/client.gen.ts
@@ -251,10 +251,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-ky/import-file-extension-ts/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-ky/import-file-extension-ts/client/client.gen.ts
index 48a78ffe9d..974d881b8b 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-ky/import-file-extension-ts/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-ky/import-file-extension-ts/client/client.gen.ts
@@ -251,10 +251,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-ky/sdk-client-optional/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-ky/sdk-client-optional/client/client.gen.ts
index 27da91a539..005420333b 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-ky/sdk-client-optional/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-ky/sdk-client-optional/client/client.gen.ts
@@ -251,10 +251,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-ky/sdk-client-required/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-ky/sdk-client-required/client/client.gen.ts
index 27da91a539..005420333b 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-ky/sdk-client-required/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-ky/sdk-client-required/client/client.gen.ts
@@ -251,10 +251,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-ky/tsconfig-node16-sdk/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-ky/tsconfig-node16-sdk/client/client.gen.ts
index e214d50fc2..af6d3948d3 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-ky/tsconfig-node16-sdk/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-ky/tsconfig-node16-sdk/client/client.gen.ts
@@ -251,10 +251,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-ky/tsconfig-nodenext-sdk/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-ky/tsconfig-nodenext-sdk/client/client.gen.ts
index e214d50fc2..af6d3948d3 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-ky/tsconfig-nodenext-sdk/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-ky/tsconfig-nodenext-sdk/client/client.gen.ts
@@ -251,10 +251,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-next/base-url-false/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-next/base-url-false/client/client.gen.ts
index f87d22dab4..7ad3017a86 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-next/base-url-false/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-next/base-url-false/client/client.gen.ts
@@ -144,10 +144,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return {
             data: response.body,
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-next/base-url-number/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-next/base-url-number/client/client.gen.ts
index f87d22dab4..7ad3017a86 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-next/base-url-number/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-next/base-url-number/client/client.gen.ts
@@ -144,10 +144,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return {
             data: response.body,
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-next/base-url-strict/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-next/base-url-strict/client/client.gen.ts
index f87d22dab4..7ad3017a86 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-next/base-url-strict/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-next/base-url-strict/client/client.gen.ts
@@ -144,10 +144,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return {
             data: response.body,
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-next/base-url-string/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-next/base-url-string/client/client.gen.ts
index f87d22dab4..7ad3017a86 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-next/base-url-string/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-next/base-url-string/client/client.gen.ts
@@ -144,10 +144,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return {
             data: response.body,
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-next/clean-false/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-next/clean-false/client/client.gen.ts
index f87d22dab4..7ad3017a86 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-next/clean-false/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-next/clean-false/client/client.gen.ts
@@ -144,10 +144,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return {
             data: response.body,
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-next/default/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-next/default/client/client.gen.ts
index f87d22dab4..7ad3017a86 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-next/default/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-next/default/client/client.gen.ts
@@ -144,10 +144,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return {
             data: response.body,
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-next/import-file-extension-ts/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-next/import-file-extension-ts/client/client.gen.ts
index 6e46265631..caf49a4c36 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-next/import-file-extension-ts/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-next/import-file-extension-ts/client/client.gen.ts
@@ -144,10 +144,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return {
             data: response.body,
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-next/sdk-client-optional/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-next/sdk-client-optional/client/client.gen.ts
index f87d22dab4..7ad3017a86 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-next/sdk-client-optional/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-next/sdk-client-optional/client/client.gen.ts
@@ -144,10 +144,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return {
             data: response.body,
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-next/sdk-client-required/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-next/sdk-client-required/client/client.gen.ts
index f87d22dab4..7ad3017a86 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-next/sdk-client-required/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-next/sdk-client-required/client/client.gen.ts
@@ -144,10 +144,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return {
             data: response.body,
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-next/tsconfig-node16-sdk/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-next/tsconfig-node16-sdk/client/client.gen.ts
index 60162e9e20..35c48e36f5 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-next/tsconfig-node16-sdk/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-next/tsconfig-node16-sdk/client/client.gen.ts
@@ -144,10 +144,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return {
             data: response.body,
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-next/tsconfig-nodenext-sdk/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-next/tsconfig-nodenext-sdk/client/client.gen.ts
index 60162e9e20..35c48e36f5 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-next/tsconfig-nodenext-sdk/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/@hey-api/client-next/tsconfig-nodenext-sdk/client/client.gen.ts
@@ -144,10 +144,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return {
             data: response.body,
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/client-custom/bundle/client/index.cjs b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/client-custom/bundle/client/index.cjs
index c6a7b18f3b..faef514013 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/client-custom/bundle/client/index.cjs
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/clients/client-custom/bundle/client/index.cjs
@@ -399,10 +399,14 @@ const createClient = (config = {}) => {
 				case "arrayBuffer":
 				case "blob":
 				case "formData":
-				case "json":
 				case "text":
 					data = await response[parseAs]();
 					break;
+				case "json": {
+					const text = await response.text();
+					data = text ? JSON.parse(text) : {};
+					break;
+				}
 				case "stream": return {
 					data: response.body,
 					...result
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/headers/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/headers/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/headers/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/headers/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/internal-name-conflict/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/internal-name-conflict/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/internal-name-conflict/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/internal-name-conflict/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/pagination-ref/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/pagination-ref/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/pagination-ref/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/pagination-ref/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/parameter-explode-false/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/parameter-explode-false/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/parameter-explode-false/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/parameter-explode-false/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@hey-api/client-fetch/sdk-nested-classes-instance/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@hey-api/client-fetch/sdk-nested-classes-instance/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@hey-api/client-fetch/sdk-nested-classes-instance/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@hey-api/client-fetch/sdk-nested-classes-instance/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@hey-api/client-fetch/sdk-nested-classes/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@hey-api/client-fetch/sdk-nested-classes/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@hey-api/client-fetch/sdk-nested-classes/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@hey-api/client-fetch/sdk-nested-classes/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@hey-api/sdk/default/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@hey-api/sdk/default/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@hey-api/sdk/default/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@hey-api/sdk/default/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@hey-api/sdk/instance/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@hey-api/sdk/instance/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@hey-api/sdk/instance/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@hey-api/sdk/instance/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@hey-api/sdk/throwOnError/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@hey-api/sdk/throwOnError/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@hey-api/sdk/throwOnError/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@hey-api/sdk/throwOnError/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@hey-api/transformers/type-format-valibot/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@hey-api/transformers/type-format-valibot/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@hey-api/transformers/type-format-valibot/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@hey-api/transformers/type-format-valibot/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@hey-api/transformers/type-format-zod/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@hey-api/transformers/type-format-zod/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@hey-api/transformers/type-format-zod/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@hey-api/transformers/type-format-zod/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@hey-api/typescript/transforms-read-write-custom-name/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@hey-api/typescript/transforms-read-write-custom-name/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@hey-api/typescript/transforms-read-write-custom-name/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@hey-api/typescript/transforms-read-write-custom-name/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@hey-api/typescript/transforms-read-write-ignore/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@hey-api/typescript/transforms-read-write-ignore/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@hey-api/typescript/transforms-read-write-ignore/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@hey-api/typescript/transforms-read-write-ignore/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@pinia/colada/asClass/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@pinia/colada/asClass/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@pinia/colada/asClass/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@pinia/colada/asClass/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@pinia/colada/fetch/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@pinia/colada/fetch/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@pinia/colada/fetch/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@pinia/colada/fetch/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@tanstack/angular-query-experimental/asClass/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@tanstack/angular-query-experimental/asClass/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@tanstack/angular-query-experimental/asClass/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@tanstack/angular-query-experimental/asClass/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@tanstack/angular-query-experimental/fetch/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@tanstack/angular-query-experimental/fetch/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@tanstack/angular-query-experimental/fetch/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@tanstack/angular-query-experimental/fetch/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@tanstack/angular-query-experimental/name-builder/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@tanstack/angular-query-experimental/name-builder/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@tanstack/angular-query-experimental/name-builder/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@tanstack/angular-query-experimental/name-builder/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@tanstack/react-query/asClass/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@tanstack/react-query/asClass/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@tanstack/react-query/asClass/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@tanstack/react-query/asClass/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@tanstack/react-query/fetch/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@tanstack/react-query/fetch/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@tanstack/react-query/fetch/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@tanstack/react-query/fetch/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@tanstack/react-query/name-builder/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@tanstack/react-query/name-builder/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@tanstack/react-query/name-builder/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@tanstack/react-query/name-builder/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@tanstack/solid-query/asClass/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@tanstack/solid-query/asClass/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@tanstack/solid-query/asClass/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@tanstack/solid-query/asClass/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@tanstack/solid-query/fetch/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@tanstack/solid-query/fetch/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@tanstack/solid-query/fetch/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@tanstack/solid-query/fetch/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@tanstack/solid-query/name-builder/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@tanstack/solid-query/name-builder/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@tanstack/solid-query/name-builder/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@tanstack/solid-query/name-builder/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@tanstack/svelte-query/asClass/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@tanstack/svelte-query/asClass/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@tanstack/svelte-query/asClass/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@tanstack/svelte-query/asClass/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@tanstack/svelte-query/fetch/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@tanstack/svelte-query/fetch/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@tanstack/svelte-query/fetch/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@tanstack/svelte-query/fetch/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@tanstack/svelte-query/name-builder/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@tanstack/svelte-query/name-builder/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@tanstack/svelte-query/name-builder/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@tanstack/svelte-query/name-builder/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@tanstack/vue-query/asClass/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@tanstack/vue-query/asClass/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@tanstack/vue-query/asClass/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@tanstack/vue-query/asClass/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@tanstack/vue-query/fetch/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@tanstack/vue-query/fetch/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@tanstack/vue-query/fetch/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@tanstack/vue-query/fetch/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@tanstack/vue-query/name-builder/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@tanstack/vue-query/name-builder/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@tanstack/vue-query/name-builder/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/plugins/@tanstack/vue-query/name-builder/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/security-api-key/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/security-api-key/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/security-api-key/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/security-api-key/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/security-false/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/security-false/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/security-false/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/security-false/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/security-http-bearer/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/security-http-bearer/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/security-http-bearer/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/security-http-bearer/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/security-oauth2/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/security-oauth2/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/security-oauth2/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/security-oauth2/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/security-open-id-connect/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/security-open-id-connect/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/security-open-id-connect/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/security-open-id-connect/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/servers/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/servers/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/servers/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/servers/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/sse-fetch/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/sse-fetch/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/sse-fetch/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/sse-fetch/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/sse-next/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/sse-next/client/client.gen.ts
index f87d22dab4..7ad3017a86 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/sse-next/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/sse-next/client/client.gen.ts
@@ -144,10 +144,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return {
             data: response.body,
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/transformers-all-of/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/transformers-all-of/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/transformers-all-of/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/transformers-all-of/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/transformers-any-of-null/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/transformers-any-of-null/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/transformers-any-of-null/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/transformers-any-of-null/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/transformers-array/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/transformers-array/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/transformers-array/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/transformers-array/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/transformers-recursive/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/transformers-recursive/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/transformers-recursive/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/transformers-recursive/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/transforms-read-write/client/client.gen.ts b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/transforms-read-write/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/transforms-read-write/client/client.gen.ts
+++ b/packages/openapi-ts-tests/main/test/__snapshots__/3.1.x/transforms-read-write/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/sdks/__snapshots__/method-class-conflict/class/client/client.gen.ts b/packages/openapi-ts-tests/sdks/__snapshots__/method-class-conflict/class/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/sdks/__snapshots__/method-class-conflict/class/client/client.gen.ts
+++ b/packages/openapi-ts-tests/sdks/__snapshots__/method-class-conflict/class/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/sdks/__snapshots__/method-class-conflict/flat/client/client.gen.ts b/packages/openapi-ts-tests/sdks/__snapshots__/method-class-conflict/flat/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/sdks/__snapshots__/method-class-conflict/flat/client/client.gen.ts
+++ b/packages/openapi-ts-tests/sdks/__snapshots__/method-class-conflict/flat/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/sdks/__snapshots__/method-class-conflict/instance/client/client.gen.ts b/packages/openapi-ts-tests/sdks/__snapshots__/method-class-conflict/instance/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/sdks/__snapshots__/method-class-conflict/instance/client/client.gen.ts
+++ b/packages/openapi-ts-tests/sdks/__snapshots__/method-class-conflict/instance/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/sdks/__snapshots__/opencode/export-all/client/client.gen.ts b/packages/openapi-ts-tests/sdks/__snapshots__/opencode/export-all/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/sdks/__snapshots__/opencode/export-all/client/client.gen.ts
+++ b/packages/openapi-ts-tests/sdks/__snapshots__/opencode/export-all/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/sdks/__snapshots__/opencode/flat/client/client.gen.ts b/packages/openapi-ts-tests/sdks/__snapshots__/opencode/flat/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/sdks/__snapshots__/opencode/flat/client/client.gen.ts
+++ b/packages/openapi-ts-tests/sdks/__snapshots__/opencode/flat/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body
diff --git a/packages/openapi-ts-tests/sdks/__snapshots__/opencode/grouped/client/client.gen.ts b/packages/openapi-ts-tests/sdks/__snapshots__/opencode/grouped/client/client.gen.ts
index bf75e621b5..d4cbcce509 100644
--- a/packages/openapi-ts-tests/sdks/__snapshots__/opencode/grouped/client/client.gen.ts
+++ b/packages/openapi-ts-tests/sdks/__snapshots__/opencode/grouped/client/client.gen.ts
@@ -182,10 +182,16 @@ export const createClient = (config: Config = {}): Client => {
         case 'arrayBuffer':
         case 'blob':
         case 'formData':
-        case 'json':
         case 'text':
           data = await response[parseAs]();
           break;
+        case 'json': {
+          // Some servers return 200 with no Content-Length and empty body.
+          // response.json() would throw; read as text and parse if non-empty.
+          const text = await response.text();
+          data = text ? JSON.parse(text) : {};
+          break;
+        }
         case 'stream':
           return opts.responseStyle === 'data'
             ? response.body

From 2af4d9ab56293c042459e6ae31787cd628be6037 Mon Sep 17 00:00:00 2001
From: Lubos <lubos@heyapi.dev>
Date: Tue, 13 Jan 2026 15:48:44 +0800
Subject: [PATCH 6/8] Update patch versions and fix JSON parsing error

Fix JSON parsing error on empty response bodies without Content-Length header for the @hey-api/client-fetch plugin.
---
 .changeset/tame-olives-brake.md | 5 +++++
 1 file changed, 5 insertions(+)
 create mode 100644 .changeset/tame-olives-brake.md

diff --git a/.changeset/tame-olives-brake.md b/.changeset/tame-olives-brake.md
new file mode 100644
index 0000000000..e81918b8a4
--- /dev/null
+++ b/.changeset/tame-olives-brake.md
@@ -0,0 +1,5 @@
+---
+"@hey-api/openapi-ts": patch
+---
+
+**plugin(@hey-api/client-fetch)**: fix: JSON parsing error on empty response bodies without Content-Length header

From c0563fbd0f0ec66d25e5316bda0274380ac26639 Mon Sep 17 00:00:00 2001
From: Lubos <lubos@heyapi.dev>
Date: Tue, 13 Jan 2026 15:53:46 +0800
Subject: [PATCH 7/8] Fix JSON parsing error for empty response bodies

Fixes a JSON parsing error when handling empty response bodies that lack a Content-Length header.
---
 .changeset/tame-solives-brake.md | 5 +++++
 1 file changed, 5 insertions(+)
 create mode 100644 .changeset/tame-solives-brake.md

diff --git a/.changeset/tame-solives-brake.md b/.changeset/tame-solives-brake.md
new file mode 100644
index 0000000000..f92ff33918
--- /dev/null
+++ b/.changeset/tame-solives-brake.md
@@ -0,0 +1,5 @@
+---
+"@hey-api/openapi-ts": patch
+---
+
+**plugin(@hey-api/client-ky)**: fix: JSON parsing error on empty response bodies without Content-Length header

From 8428ca5152c66d393bcfee9570a6c1d7ad1155c7 Mon Sep 17 00:00:00 2001
From: Lubos <lubos@heyapi.dev>
Date: Tue, 13 Jan 2026 15:54:25 +0800
Subject: [PATCH 8/8] Fix JSON parsing error for empty response bodies

Fixes a JSON parsing error when handling empty response bodies that lack a Content-Length header.
---
 .changeset/tame-dolives-brake.md | 5 +++++
 1 file changed, 5 insertions(+)
 create mode 100644 .changeset/tame-dolives-brake.md

diff --git a/.changeset/tame-dolives-brake.md b/.changeset/tame-dolives-brake.md
new file mode 100644
index 0000000000..18de6a8bb2
--- /dev/null
+++ b/.changeset/tame-dolives-brake.md
@@ -0,0 +1,5 @@
+---
+"@hey-api/openapi-ts": patch
+---
+
+**plugin(@hey-api/client-next)**: fix: JSON parsing error on empty response bodies without Content-Length header