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
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
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
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/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/custom-client/src/client.ts b/packages/custom-client/src/client.ts
index 2a5af631ac..4624d75001 100644
--- a/packages/custom-client/src/client.ts
+++ b/packages/custom-client/src/client.ts
@@ -111,10 +111,16 @@ 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/__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
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-fetch/bundle/client.ts b/packages/openapi-ts/src/plugins/@hey-api/client-fetch/bundle/client.ts
index dafdbd222f..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
@@ -180,10 +180,16 @@ 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/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-ky/bundle/client.ts b/packages/openapi-ts/src/plugins/@hey-api/client-ky/bundle/client.ts
index 7bfbf95908..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
@@ -249,10 +249,16 @@ 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/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' });
 
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..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
@@ -142,10 +142,16 @@ 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,