diff --git a/README.md b/README.md
index 17025cdc..c51d5a87 100644
--- a/README.md
+++ b/README.md
@@ -87,6 +87,16 @@ yarn add @openfga/sdk
 
 ### Supported Runtimes
 
+The SDK ships with both CommonJS and ES Module builds, and should work out of the box in Node.js, Deno, Cloudflare Workers, and modern bundlers.
+
+```javascript
+// CommonJS
+const { OpenFgaClient } = require("@openfga/sdk");
+
+// ES Modules
+import { OpenFgaClient } from "@openfga/sdk";
+```
+
 For details on the supported Node.js versions and our support policy, see [SUPPORTED_RUNTIMES.md](./SUPPORTED_RUNTIMES.md).
 
 ## Getting Started
@@ -102,7 +112,7 @@ We strongly recommend you initialize the `OpenFgaClient` only once and then re-u
 #### No Credentials
 
 ```javascript
-const { OpenFgaClient } = require('@openfga/sdk'); // OR import { OpenFgaClient } from '@openfga/sdk';
+import { OpenFgaClient } from '@openfga/sdk';
 
 const fgaClient = new OpenFgaClient({
   apiUrl: process.env.FGA_API_URL, // required
@@ -114,7 +124,7 @@ const fgaClient = new OpenFgaClient({
 #### API Token
 
 ```javascript
-const { OpenFgaClient, CredentialsMethod } = require('@openfga/sdk'); // OR import { OpenFgaClient, CredentialsMethod } from '@openfga/sdk';
+import { OpenFgaClient, CredentialsMethod } from '@openfga/sdk';
 
 const fgaClient = new OpenFgaClient({
   apiUrl: process.env.FGA_API_URL, // required
@@ -132,7 +142,7 @@ const fgaClient = new OpenFgaClient({
 #### Client Credentials
 
 ```javascript
-const { OpenFgaClient, CredentialsMethod } = require('@openfga/sdk'); // OR import { OpenFgaClient, CredentialsMethod } from '@openfga/sdk';
+import { OpenFgaClient, CredentialsMethod } from '@openfga/sdk';
 
 const fgaClient = new OpenFgaClient({
   apiUrl: process.env.FGA_API_URL, // required
@@ -157,7 +167,7 @@ const fgaClient = new OpenFgaClient({
 You can set default headers that will be sent with every request during client initialization:
 
 ```javascript
-const { OpenFgaClient } = require('@openfga/sdk'); // OR import { OpenFgaClient } from '@openfga/sdk';
+import { OpenFgaClient } from '@openfga/sdk';
 
 const fgaClient = new OpenFgaClient({
   apiUrl: process.env.FGA_API_URL,
@@ -195,7 +205,7 @@ const result = await fgaClient.check({
 The SDK uses the native `fetch` API by default. You can provide a custom `HttpClient` to control the underlying HTTP behavior.
 
 ```javascript
-const { OpenFgaClient } = require('@openfga/sdk'); // OR import { OpenFgaClient } from '@openfga/sdk';
+import { OpenFgaClient } from '@openfga/sdk';
 
 const fgaClient = new OpenFgaClient(
   {
@@ -954,7 +964,7 @@ This is useful when:
 #### Example: Calling a Custom Endpoint with POST
 
 ```javascript
-const { OpenFgaClient } = require('@openfga/sdk');
+import { OpenFgaClient } from "@openfga/sdk";
 
 const fgaClient = new OpenFgaClient({
   apiUrl: process.env.FGA_API_URL,
@@ -1056,7 +1066,7 @@ To customize this behavior, create an object with `maxRetry` and `minWaitInMs` p
 Apply your custom retry values by setting to `retryParams` on the configuration object passed to the `OpenFgaClient` call.
 
 ```javascript
-const { OpenFgaClient } = require('@openfga/sdk'); // OR import { OpenFgaClient } from '@openfga/sdk';
+import { OpenFgaClient } from '@openfga/sdk';
 
 const fgaClient = new OpenFgaClient({
   apiUrl: process.env.FGA_API_URL, // required
diff --git a/api.ts b/api.ts
index 85bc26ea..8d0abc96 100644
--- a/api.ts
+++ b/api.ts
@@ -11,7 +11,7 @@
  */
 
 
-import { BaseAPI } from "./base";
+import { BaseAPI } from "./base.js";
 import {
   DUMMY_BASE_URL,
   setSearchParams,
@@ -28,12 +28,12 @@ import {
   RequestBuilderParams,
   RequestBuilderOptions,
   RequestBuilder,
-} from "./common";
+} from "./common.js";
 
 export type { HttpMethod, RequestBuilderParams, RequestBuilderOptions };
-import { Configuration } from "./configuration";
-import { Credentials } from "./credentials";
-import { assertParamExists } from "./validation";
+import { Configuration } from "./configuration.js";
+import { Credentials } from "./credentials/index.js";
+import { assertParamExists } from "./validation.js";
 
 import {
   AbortedMessageResponse,
@@ -122,8 +122,8 @@ import {
   WriteRequest,
   WriteRequestDeletes,
   WriteRequestWrites,
-} from "./apiModel";
-import { TelemetryAttribute, TelemetryAttributes } from "./telemetry/attributes";
+} from "./apiModel.js";
+import { TelemetryAttribute, TelemetryAttributes } from "./telemetry/attributes.js";
 
 
 /**
diff --git a/base.ts b/base.ts
index ed6525d6..25ec5a5a 100644
--- a/base.ts
+++ b/base.ts
@@ -1,6 +1,6 @@
-import { Configuration, UserConfigurationParams } from "./configuration";
-import { HttpClient } from "./common";
-import { Credentials } from "./credentials";
+import { Configuration, UserConfigurationParams } from "./configuration.js";
+import { HttpClient } from "./common.js";
+import { Credentials } from "./credentials/index.js";
 
 const DEFAULT_CONNECTION_TIMEOUT_IN_MS = 10000;
 
diff --git a/client.ts b/client.ts
index 1629126b..3d1e87bf 100644
--- a/client.ts
+++ b/client.ts
@@ -1,7 +1,7 @@
-import asyncPool = require("tiny-async-pool");
+import { asyncPool } from "./utils/utils-lite/async-pool.js";
 
-import { OpenFgaApi, HttpMethod, RequestBuilderParams, RequestBuilderOptions } from "./api";
-import type { FgaResponse, HttpClient } from "./common";
+import { OpenFgaApi, HttpMethod, RequestBuilderParams, RequestBuilderOptions } from "./api.js";
+import type { FgaResponse, HttpClient } from "./common.js";
 export type { HttpMethod, RequestBuilderParams, RequestBuilderOptions };
 import {
   Assertion,
@@ -40,19 +40,19 @@ import {
   WriteRequest,
   WriteRequestWritesOnDuplicate,
   WriteRequestDeletesOnMissing,
-} from "./apiModel";
-import { BaseAPI } from "./base";
-import { CallResult, PromiseResult } from "./common";
-import { Configuration, RetryParams, UserConfigurationParams } from "./configuration";
-import { FgaApiAuthenticationError, FgaRequiredParamError, FgaValidationError } from "./errors";
+} from "./apiModel.js";
+import { BaseAPI } from "./base.js";
+import { CallResult, PromiseResult } from "./common.js";
+import { Configuration, RetryParams, UserConfigurationParams } from "./configuration.js";
+import { FgaApiAuthenticationError, FgaRequiredParamError, FgaValidationError } from "./errors.js";
 import {
   chunkArray,
   generateRandomIdWithNonUniqueFallback,
   setHeaderIfNotSet,
-} from "./utils";
-import { isWellFormedUlidString } from "./validation";
-import SdkConstants from "./constants";
-import { parseNDJSONStream } from "./streaming";
+} from "./utils/index.js";
+import { isWellFormedUlidString } from "./validation.js";
+import SdkConstants from "./constants/index.js";
+import { parseNDJSONStream } from "./streaming.js";
 
 export type UserClientConfigurationParams = UserConfigurationParams & {
   storeId?: string;
diff --git a/common.ts b/common.ts
index bed8217c..5cbb6c31 100644
--- a/common.ts
+++ b/common.ts
@@ -1,6 +1,6 @@
-import { Configuration, RetryParams } from "./configuration";
-import SdkConstants from "./constants";
-import type { Credentials } from "./credentials";
+import { Configuration, RetryParams } from "./configuration.js";
+import SdkConstants from "./constants/index.js";
+import type { Credentials } from "./credentials/index.js";
 import {
   FgaApiError,
   FgaApiInternalError,
@@ -11,11 +11,11 @@ import {
   FgaError,
   FgaValidationError,
   HttpErrorContext,
-} from "./errors";
-import { setNotEnumerableProperty } from "./utils";
-import { TelemetryAttribute, TelemetryAttributes } from "./telemetry/attributes";
-import { TelemetryConfiguration } from "./telemetry/configuration";
-import { TelemetryHistograms } from "./telemetry/histograms";
+} from "./errors.js";
+import { setNotEnumerableProperty } from "./utils/index.js";
+import { TelemetryAttribute, TelemetryAttributes } from "./telemetry/attributes.js";
+import { TelemetryConfiguration } from "./telemetry/configuration.js";
+import { TelemetryHistograms } from "./telemetry/histograms.js";
 
 /**
  *
diff --git a/configuration.ts b/configuration.ts
index 9e61a8e4..6b9d9295 100644
--- a/configuration.ts
+++ b/configuration.ts
@@ -1,8 +1,8 @@
-import { ApiTokenConfig, AuthCredentialsConfig, ClientCredentialsConfig, CredentialsMethod } from "./credentials/types";
-import { FgaValidationError, } from "./errors";
-import { assertParamExists, isWellFormedUriString } from "./validation";
-import { TelemetryConfig, TelemetryConfiguration } from "./telemetry/configuration";
-import SdkConstants from "./constants";
+import { ApiTokenConfig, AuthCredentialsConfig, ClientCredentialsConfig, CredentialsMethod } from "./credentials/types.js";
+import { FgaValidationError, } from "./errors.js";
+import { assertParamExists, isWellFormedUriString } from "./validation.js";
+import { TelemetryConfig, TelemetryConfiguration } from "./telemetry/configuration.js";
+import SdkConstants from "./constants/index.js";
 
 // default maximum number of retry
 const DEFAULT_MAX_RETRY = SdkConstants.DefaultMaxRetry;
diff --git a/credentials/credentials.ts b/credentials/credentials.ts
index 1d2ef250..3bd15d06 100644
--- a/credentials/credentials.ts
+++ b/credentials/credentials.ts
@@ -13,15 +13,15 @@
 
 import * as jose from "jose";
 
-import { assertParamExists, isWellFormedUriString } from "../validation";
-import { FgaApiAuthenticationError, FgaApiError, FgaValidationError } from "../errors";
-import { attemptHttpRequest, HttpClient } from "../common";
-import { AuthCredentialsConfig, PrivateKeyJWTConfig, ClientCredentialsConfig, ClientSecretConfig, CredentialsMethod } from "./types";
-import { TelemetryAttributes } from "../telemetry/attributes";
-import { TelemetryCounters } from "../telemetry/counters";
-import { TelemetryConfiguration } from "../telemetry/configuration";
+import { assertParamExists, isWellFormedUriString } from "../validation.js";
+import { FgaApiAuthenticationError, FgaApiError, FgaValidationError } from "../errors.js";
+import { attemptHttpRequest, HttpClient } from "../common.js";
+import { AuthCredentialsConfig, PrivateKeyJWTConfig, ClientCredentialsConfig, ClientSecretConfig, CredentialsMethod } from "./types.js";
+import { TelemetryAttributes } from "../telemetry/attributes.js";
+import { TelemetryCounters } from "../telemetry/counters.js";
+import { TelemetryConfiguration } from "../telemetry/configuration.js";
 import { randomUUID } from "crypto";
-import SdkConstants from "../constants";
+import SdkConstants from "../constants/index.js";
 
 interface ClientSecretRequest {
   client_id: string;
diff --git a/credentials/index.ts b/credentials/index.ts
index b3fce532..af6c912c 100644
--- a/credentials/index.ts
+++ b/credentials/index.ts
@@ -11,5 +11,5 @@
  */
 
 
-export * from "./credentials";
-export * from "./types";
+export * from "./credentials.js";
+export * from "./types.js";
diff --git a/errors.ts b/errors.ts
index 1951fb89..78f315d2 100644
--- a/errors.ts
+++ b/errors.ts
@@ -2,7 +2,21 @@ import {
   ErrorCode,
   InternalErrorCode,
   NotFoundErrorCode,
-} from "./apiModel";
+} from "./apiModel.js";
+
+/**
+ * Context extracted from a failed HTTP request/response,
+ * used to construct SDK error classes without coupling to any HTTP library.
+ */
+export interface HttpErrorContext {
+  status?: number;
+  statusText?: string;
+  headers?: Record<string, string>;
+  data?: any;
+  requestUrl?: string;
+  requestMethod?: string;
+  requestData?: any;
+}
 
 /**
  * Context extracted from a failed HTTP request/response,
diff --git a/index.ts b/index.ts
index aa9eee6f..991963f0 100644
--- a/index.ts
+++ b/index.ts
@@ -11,17 +11,17 @@
  */
 
 
-export * from "./api";
-export * from "./client";
-export * from "./apiModel";
-export { Configuration, UserConfigurationParams, GetDefaultRetryParams } from "./configuration";
-export { Credentials, CredentialsMethod } from "./credentials";
-export * from "./telemetry/attributes";
-export * from "./telemetry/configuration";
-export * from "./telemetry/counters";
-export * from "./telemetry/histograms";
-export * from "./telemetry/metrics";
-export * from "./errors";
-export { FgaResponse, HttpClient, CallResult, PromiseResult } from "./common";
-export { parseNDJSONStream } from "./streaming";
+export * from "./api.js";
+export * from "./client.js";
+export * from "./apiModel.js";
+export { Configuration, UserConfigurationParams, GetDefaultRetryParams } from "./configuration.js";
+export { Credentials, CredentialsMethod } from "./credentials/index.js";
+export * from "./telemetry/attributes.js";
+export * from "./telemetry/configuration.js";
+export * from "./telemetry/counters.js";
+export * from "./telemetry/histograms.js";
+export * from "./telemetry/metrics.js";
+export * from "./errors.js";
+export { FgaResponse, HttpClient, CallResult, PromiseResult } from "./common.js";
+export { parseNDJSONStream } from "./streaming.js";
 
diff --git a/package-lock.json b/package-lock.json
index f370ba93..8011cd13 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -10,13 +10,11 @@
       "license": "Apache-2.0",
       "dependencies": {
         "@opentelemetry/api": "^1.9.1",
-        "jose": "5.10.0",
-        "tiny-async-pool": "^2.1.0"
+        "jose": "5.10.0"
       },
       "devDependencies": {
         "@types/jest": "30.0.0",
         "@types/node": "^25.6.0",
-        "@types/tiny-async-pool": "^2.0.3",
         "@typescript-eslint/eslint-plugin": "^8.59.2",
         "@typescript-eslint/parser": "^8.59.2",
         "eslint": "^10.3.0",
@@ -1479,13 +1477,6 @@
       "dev": true,
       "license": "MIT"
     },
-    "node_modules/@types/tiny-async-pool": {
-      "version": "2.0.3",
-      "resolved": "https://registry.npmjs.org/@types/tiny-async-pool/-/tiny-async-pool-2.0.3.tgz",
-      "integrity": "sha512-n3l1s538tKo9RBoHs4I3DG/VmD3VYhF5mHcgu1sU4Lq7JCNBtxnpBy3OkWSbZsp5r5QOuplh2UkXXXwufoAuNQ==",
-      "dev": true,
-      "license": "MIT"
-    },
     "node_modules/@types/yargs": {
       "version": "17.0.35",
       "resolved": "https://registry.npmjs.org/@types/yargs/-/yargs-17.0.35.tgz",
@@ -2228,9 +2219,9 @@
       }
     },
     "node_modules/baseline-browser-mapping": {
-      "version": "2.10.40",
-      "resolved": "https://registry.npmjs.org/baseline-browser-mapping/-/baseline-browser-mapping-2.10.40.tgz",
-      "integrity": "sha512-BSSLZ9/Cjjv7Gtj5B68ZzXcXUg8iOf3fme+FCuh8rC/Go+Kmh8cox7M3A8dolou16s64QjLPOSdngh7GxXvkSw==",
+      "version": "2.11.4",
+      "resolved": "https://registry.npmjs.org/baseline-browser-mapping/-/baseline-browser-mapping-2.11.4.tgz",
+      "integrity": "sha512-s4+sLr9mZ/CyqeRritFeYV/Zx73OAtmaHn6kkBS1XRoJn1hrg3xIDUcpicAEX68tkcIN0iBCgti31C8zxtkhsQ==",
       "dev": true,
       "license": "Apache-2.0",
       "bin": {
@@ -2241,22 +2232,22 @@
       }
     },
     "node_modules/brace-expansion": {
-      "version": "5.0.6",
-      "resolved": "https://registry.npmjs.org/brace-expansion/-/brace-expansion-5.0.6.tgz",
-      "integrity": "sha512-kLpxurY4Z4r9sgMsyG0Z9uzsBlgiU/EFKhj/h91/8yHu0edo7XuixOIH3VcJ8kkxs6/jPzoI6U9Vj3WqbMQ94g==",
+      "version": "5.0.8",
+      "resolved": "https://registry.npmjs.org/brace-expansion/-/brace-expansion-5.0.8.tgz",
+      "integrity": "sha512-JZyDyq3D4AUifKTPOB7DELf6XsB3WdPuNxCtob1vFXPsSXhdAiHBWJ/tJ8HAc9aH84BK+5JFZLNkJKx3G9kzQg==",
       "dev": true,
       "license": "MIT",
       "dependencies": {
         "balanced-match": "^4.0.2"
       },
       "engines": {
-        "node": "18 || 20 || >=22"
+        "node": "20 || >=22"
       }
     },
     "node_modules/browserslist": {
-      "version": "4.28.4",
-      "resolved": "https://registry.npmjs.org/browserslist/-/browserslist-4.28.4.tgz",
-      "integrity": "sha512-MTc8i/x9jBQd1iMw2CFGS+rwMa07eYjLR0CCTLDACl9xhxy+nIs3KeML/biicXtk9JrZ6dnnTatmc7ErPXIxqw==",
+      "version": "4.28.7",
+      "resolved": "https://registry.npmjs.org/browserslist/-/browserslist-4.28.7.tgz",
+      "integrity": "sha512-JxV13hNrFxqjOc8alRbq9dK1MM79NEXYpma2B2J4wAtpWS5zIEIKqWPGCl7N4o7Uc7B7itylh7SuDujATRyyTw==",
       "dev": true,
       "funding": [
         {
@@ -2274,10 +2265,10 @@
       ],
       "license": "MIT",
       "dependencies": {
-        "baseline-browser-mapping": "^2.10.38",
-        "caniuse-lite": "^1.0.30001799",
-        "electron-to-chromium": "^1.5.376",
-        "node-releases": "^2.0.48",
+        "baseline-browser-mapping": "^2.10.44",
+        "caniuse-lite": "^1.0.30001806",
+        "electron-to-chromium": "^1.5.393",
+        "node-releases": "^2.0.51",
         "update-browserslist-db": "^1.2.3"
       },
       "bin": {
@@ -2338,9 +2329,9 @@
       }
     },
     "node_modules/caniuse-lite": {
-      "version": "1.0.30001799",
-      "resolved": "https://registry.npmjs.org/caniuse-lite/-/caniuse-lite-1.0.30001799.tgz",
-      "integrity": "sha512-hG1bReV+OUU+MOqK4t/ZWI0tZOyz3rqS9XuhOUz1cIcbwBKjOyJEJuw9ER5JuNyqxNk8u/JUVbGibBOL1yrjFw==",
+      "version": "1.0.30001806",
+      "resolved": "https://registry.npmjs.org/caniuse-lite/-/caniuse-lite-1.0.30001806.tgz",
+      "integrity": "sha512-72Cuvd95zbSYPKq6Fhg8eDJRlzgWDf7/mtoZv6Qe/DYNCEBdNxoA3+rZAU2ZhGCpZlns3EssFavaZomckT5Uuw==",
       "dev": true,
       "funding": [
         {
@@ -2524,13 +2515,6 @@
       "dev": true,
       "license": "MIT"
     },
-    "node_modules/concat-map": {
-      "version": "0.0.1",
-      "resolved": "https://registry.npmjs.org/concat-map/-/concat-map-0.0.1.tgz",
-      "integrity": "sha512-/Srv4dswyQNBfohGpz9o6Yb3Gz3SrUDqBH5rTuhGR7ahtlbYKnVxw2bCFMRljaA7EXHaXZ8wsHdodFvbkhKmqg==",
-      "dev": true,
-      "license": "MIT"
-    },
     "node_modules/convert-source-map": {
       "version": "2.0.0",
       "resolved": "https://registry.npmjs.org/convert-source-map/-/convert-source-map-2.0.0.tgz",
@@ -2621,9 +2605,9 @@
       "license": "MIT"
     },
     "node_modules/electron-to-chromium": {
-      "version": "1.5.380",
-      "resolved": "https://registry.npmjs.org/electron-to-chromium/-/electron-to-chromium-1.5.380.tgz",
-      "integrity": "sha512-W6d5AbuEoRayO447cqrg6lKJIlscgRnnxOZl/08kfV71BQDoEBC7Wwis68z87LjyK6f4kWyTaubuDbhHKrZkbA==",
+      "version": "1.5.396",
+      "resolved": "https://registry.npmjs.org/electron-to-chromium/-/electron-to-chromium-1.5.396.tgz",
+      "integrity": "sha512-yHiw2Y3C3H9U6TMbOfoWK/BPreiOPXRfTWPBwQBoZG6/8TB6eOPnsy5oaRYuatR7Fw2SJ4kKforgufeo7fq0EQ==",
       "dev": true,
       "license": "ISC"
     },
@@ -3126,23 +3110,6 @@
         "node": ">=10.13.0"
       }
     },
-    "node_modules/glob/node_modules/balanced-match": {
-      "version": "1.0.2",
-      "resolved": "https://registry.npmjs.org/balanced-match/-/balanced-match-1.0.2.tgz",
-      "integrity": "sha512-3oSeUO0TMV67hN1AmbXsK4yaqU7tjiHlbxRDZOpH0KW9+CeX4bRAaX0Anxt0tx2MrpRpWwQaPwIlISEJhYU5Pw==",
-      "dev": true,
-      "license": "MIT"
-    },
-    "node_modules/glob/node_modules/brace-expansion": {
-      "version": "2.1.0",
-      "resolved": "https://registry.npmjs.org/brace-expansion/-/brace-expansion-2.1.0.tgz",
-      "integrity": "sha512-TN1kCZAgdgweJhWWpgKYrQaMNHcDULHkWwQIspdtjV4Y5aurRdZpjAqn6yX3FPqTA9ngHCc4hJxMAMgGfve85w==",
-      "dev": true,
-      "license": "MIT",
-      "dependencies": {
-        "balanced-match": "^1.0.0"
-      }
-    },
     "node_modules/glob/node_modules/minimatch": {
       "version": "9.0.9",
       "resolved": "https://registry.npmjs.org/minimatch/-/minimatch-9.0.9.tgz",
@@ -4389,9 +4356,9 @@
       "license": "MIT"
     },
     "node_modules/node-releases": {
-      "version": "2.0.50",
-      "resolved": "https://registry.npmjs.org/node-releases/-/node-releases-2.0.50.tgz",
-      "integrity": "sha512-J6l92tKHX6w8Jy5nO1Vuc01NoIiRGi/d6qBKVxh+IQ8Cr3b6HbVNfKiF8ZpFKufTwpwxMmce2W3iQZ861ZRyTg==",
+      "version": "2.0.51",
+      "resolved": "https://registry.npmjs.org/node-releases/-/node-releases-2.0.51.tgz",
+      "integrity": "sha512-wRNIrw4DmVLKQlbgOMdkMx27Wrpzes2hh5Jtbi2bjPd+4wJstWIqP5A+lscnqbm0xxmT5Bpg8Lec5ItEBwx6BQ==",
       "dev": true,
       "license": "MIT",
       "engines": {
@@ -5136,24 +5103,6 @@
         "node": ">=8"
       }
     },
-    "node_modules/test-exclude/node_modules/balanced-match": {
-      "version": "1.0.2",
-      "resolved": "https://registry.npmjs.org/balanced-match/-/balanced-match-1.0.2.tgz",
-      "integrity": "sha512-3oSeUO0TMV67hN1AmbXsK4yaqU7tjiHlbxRDZOpH0KW9+CeX4bRAaX0Anxt0tx2MrpRpWwQaPwIlISEJhYU5Pw==",
-      "dev": true,
-      "license": "MIT"
-    },
-    "node_modules/test-exclude/node_modules/brace-expansion": {
-      "version": "1.1.13",
-      "resolved": "https://registry.npmjs.org/brace-expansion/-/brace-expansion-1.1.13.tgz",
-      "integrity": "sha512-9ZLprWS6EENmhEOpjCYW2c8VkmOvckIJZfkr7rBW6dObmfgJ/L1GpSYW5Hpo9lDz4D1+n0Ckz8rU7FwHDQiG/w==",
-      "dev": true,
-      "license": "MIT",
-      "dependencies": {
-        "balanced-match": "^1.0.0",
-        "concat-map": "0.0.1"
-      }
-    },
     "node_modules/test-exclude/node_modules/glob": {
       "version": "7.2.3",
       "resolved": "https://registry.npmjs.org/glob/-/glob-7.2.3.tgz",
@@ -5189,12 +5138,6 @@
         "node": "*"
       }
     },
-    "node_modules/tiny-async-pool": {
-      "version": "2.1.0",
-      "resolved": "https://registry.npmjs.org/tiny-async-pool/-/tiny-async-pool-2.1.0.tgz",
-      "integrity": "sha512-ltAHPh/9k0STRQqaoUX52NH4ZQYAJz24ZAEwf1Zm+HYg3l9OXTWeqWKyYsHu40wF/F0rxd2N2bk5sLvX2qlSvg==",
-      "license": "MIT"
-    },
     "node_modules/tinyglobby": {
       "version": "0.2.16",
       "resolved": "https://registry.npmjs.org/tinyglobby/-/tinyglobby-0.2.16.tgz",
diff --git a/package.json b/package.json
index 1b432792..da91b47e 100644
--- a/package.json
+++ b/package.json
@@ -12,10 +12,22 @@
     "zanzibar"
   ],
   "license": "Apache-2.0",
-  "main": "./dist/index.js",
+  "main": "./dist/cjs/index.js",
+  "module": "./dist/esm/index.js",
   "typings": "./dist/index.d.ts",
+  "exports": {
+    ".": {
+      "types": "./dist/index.d.ts",
+      "import": "./dist/esm/index.js",
+      "require": "./dist/cjs/index.js",
+      "default": "./dist/cjs/index.js"
+    }
+  },
   "scripts": {
-    "build": "tsc --outDir dist/",
+    "build": "npm run build:cjs && npm run build:esm && npm run build:post",
+    "build:cjs": "tsc --project tsconfig.json",
+    "build:esm": "tsc --project tsconfig.esm.json",
+    "build:post": "echo '{\"type\":\"commonjs\"}' > dist/cjs/package.json && echo '{\"type\":\"module\"}' > dist/esm/package.json",
     "prepublishOnly": "rm -rf dist/ && npm run build",
     "test": "jest --config ./tests/jest.config.js",
     "lint": "eslint .",
@@ -23,13 +35,11 @@
   },
   "dependencies": {
     "@opentelemetry/api": "^1.9.1",
-    "jose": "5.10.0",
-    "tiny-async-pool": "^2.1.0"
+    "jose": "5.10.0"
   },
   "devDependencies": {
     "@types/jest": "30.0.0",
     "@types/node": "^25.6.0",
-    "@types/tiny-async-pool": "^2.0.3",
     "@typescript-eslint/eslint-plugin": "^8.59.2",
     "@typescript-eslint/parser": "^8.59.2",
     "eslint": "^10.3.0",
@@ -40,7 +50,9 @@
     "typescript": "^6.0.3"
   },
   "overrides": {
-    "js-yaml": "^4.2.0"
+    "js-yaml": "^4.2.0",
+    "brace-expansion": "^5.0.8",
+    "@babel/core": "^7.29.7"
   },
   "files": [
     "CHANGELOG.md",
diff --git a/telemetry/configuration.ts b/telemetry/configuration.ts
index ba9e770d..5839b4d6 100644
--- a/telemetry/configuration.ts
+++ b/telemetry/configuration.ts
@@ -11,9 +11,9 @@
  */
 
 
-import { FgaValidationError } from "../errors";
-import { TelemetryAttribute } from "./attributes";
-import { TelemetryMetric, MetricRecorder } from "./metrics";
+import { FgaValidationError } from "../errors.js";
+import { TelemetryAttribute } from "./attributes.js";
+import { TelemetryMetric, MetricRecorder } from "./metrics.js";
 
 /**
  * Configuration for a telemetry metric.
diff --git a/telemetry/metrics.ts b/telemetry/metrics.ts
index 44e6303e..635ce75f 100644
--- a/telemetry/metrics.ts
+++ b/telemetry/metrics.ts
@@ -12,10 +12,10 @@
 
 
 import { Counter, Histogram, Meter } from "@opentelemetry/api";
-import { TelemetryCounter } from "./counters";
-import { TelemetryHistogram } from "./histograms";
+import { TelemetryCounter } from "./counters.js";
+import { TelemetryHistogram } from "./histograms.js";
 import { metrics } from "@opentelemetry/api";
-import SdkConstants from "../constants";
+import SdkConstants from "../constants/index.js";
 
 export enum TelemetryMetric {
   CounterCredentialsRequest = "counterCredentialsRequest",
diff --git a/tests/apiExecutor.test.ts b/tests/apiExecutor.test.ts
index ee175c2b..592f711f 100644
--- a/tests/apiExecutor.test.ts
+++ b/tests/apiExecutor.test.ts
@@ -5,9 +5,9 @@ import {
   UserClientConfigurationParams,
   FgaApiNotFoundError,
   FgaApiValidationError,
-} from "../index";
-import { CredentialsMethod } from "../credentials";
-import { baseConfig, defaultConfiguration, OPENFGA_STORE_ID } from "./helpers/default-config";
+} from "../index.js";
+import { CredentialsMethod } from "../credentials/index.js";
+import { baseConfig, defaultConfiguration, OPENFGA_STORE_ID } from "./helpers/default-config.js";
 
 describe("OpenFgaClient.executeApiRequest", () => {
   const basePath = defaultConfiguration.getBasePath();
diff --git a/tests/client.test.ts b/tests/client.test.ts
index a03b3dd1..66205e9a 100644
--- a/tests/client.test.ts
+++ b/tests/client.test.ts
@@ -13,8 +13,8 @@ import {
   ErrorCode,
   ClientWriteRequestOnDuplicateWrites,
   ClientWriteRequestOnMissingDeletes,
-} from "../index";
-import { baseConfig, defaultConfiguration, getNocks } from "./helpers";
+} from "../index.js";
+import { baseConfig, defaultConfiguration, getNocks } from "./helpers/index.js";
 
 const nocks = getNocks(nock);
 
diff --git a/tests/credentials.test.ts b/tests/credentials.test.ts
index fcc2beff..4c880bd3 100644
--- a/tests/credentials.test.ts
+++ b/tests/credentials.test.ts
@@ -1,16 +1,16 @@
 import nock from "nock";
 import * as jose from "jose";
-import { Credentials, CredentialsMethod, DEFAULT_TOKEN_ENDPOINT_PATH } from "../credentials";
-import { AuthCredentialsConfig } from "../credentials/types";
-import { TelemetryConfiguration } from "../telemetry/configuration";
-import SdkConstants from "../constants";
+import { Credentials, CredentialsMethod, DEFAULT_TOKEN_ENDPOINT_PATH } from "../credentials/index.js";
+import { AuthCredentialsConfig } from "../credentials/types.js";
+import { TelemetryConfiguration } from "../telemetry/configuration.js";
+import SdkConstants from "../constants/index.js";
 import {
   OPENFGA_API_AUDIENCE,
   OPENFGA_CLIENT_ASSERTION_SIGNING_KEY,
   OPENFGA_CLIENT_ID,
   OPENFGA_CLIENT_SECRET,
-} from "./helpers/default-config";
-import { FgaApiAuthenticationError, FgaValidationError } from "../errors";
+} from "./helpers/default-config.js";
+import { FgaApiAuthenticationError, FgaValidationError } from "../errors.js";
 
 describe("Credentials", () => {
   const mockTelemetryConfig: TelemetryConfiguration = new TelemetryConfiguration({});
diff --git a/tests/errors-authentication.test.ts b/tests/errors-authentication.test.ts
index 22243fb7..ea042ff5 100644
--- a/tests/errors-authentication.test.ts
+++ b/tests/errors-authentication.test.ts
@@ -1,4 +1,4 @@
-import { FgaApiAuthenticationError, FgaApiError, HttpErrorContext } from "../errors";
+import { FgaApiAuthenticationError, FgaApiError, HttpErrorContext } from "../errors.js";
 
 describe("errors.ts", () => {
   describe("FgaApiAuthenticationError", () => {
diff --git a/tests/errors.test.ts b/tests/errors.test.ts
index 2285a99d..364d2b3b 100644
--- a/tests/errors.test.ts
+++ b/tests/errors.test.ts
@@ -1,5 +1,5 @@
-import { FgaError, FgaApiError, HttpErrorContext } from "../errors";
-import SdkConstants from "../constants";
+import { FgaError, FgaApiError, HttpErrorContext } from "../errors.js";
+import SdkConstants from "../constants/index.js";
 
 describe("errors.ts", () => {
   describe("FgaError", () => {
diff --git a/tests/fetch-http-client.test.ts b/tests/fetch-http-client.test.ts
index ea41d88e..312dbc29 100644
--- a/tests/fetch-http-client.test.ts
+++ b/tests/fetch-http-client.test.ts
@@ -1,5 +1,5 @@
-import { attemptHttpRequest, HttpClient, FgaResponse } from "../common";
-import SdkConstants from "../constants";
+import { attemptHttpRequest, HttpClient, FgaResponse } from "../common.js";
+import SdkConstants from "../constants/index.js";
 import {
   FgaError,
   FgaApiValidationError,
@@ -8,8 +8,8 @@ import {
   FgaApiRateLimitExceededError,
   FgaApiInternalError,
   FgaApiError,
-} from "../errors";
-import { OpenFgaClient } from "../client";
+} from "../errors.js";
+import { OpenFgaClient } from "../client.js";
 
 function mockHttpClient(
   fetchImpl: (url: string | URL | Request, init?: RequestInit) => Promise<Response>,
diff --git a/tests/headers.test.ts b/tests/headers.test.ts
index 95dae203..6715d215 100644
--- a/tests/headers.test.ts
+++ b/tests/headers.test.ts
@@ -1,7 +1,7 @@
 import nock from "nock";
-import { OpenFgaClient, UserClientConfigurationParams } from "../index";
-import { baseConfig } from "./helpers/default-config";
-import { CredentialsMethod } from "../credentials";
+import { OpenFgaClient, UserClientConfigurationParams } from "../index.js";
+import { baseConfig } from "./helpers/default-config.js";
+import { CredentialsMethod } from "../credentials/index.js";
 
 nock.disableNetConnect();
 
diff --git a/tests/helpers/default-config.ts b/tests/helpers/default-config.ts
index 1dd2bebd..b10853ed 100644
--- a/tests/helpers/default-config.ts
+++ b/tests/helpers/default-config.ts
@@ -1,5 +1,5 @@
-import { ClientConfiguration, UserClientConfigurationParams } from "../../client";
-import { CredentialsMethod } from "../../credentials";
+import { ClientConfiguration, UserClientConfigurationParams } from "../../client.js";
+import { CredentialsMethod } from "../../credentials/index.js";
 
 export const OPENFGA_STORE_ID = "01H0H015178Y2V4CX10C2KGHF4";
 export const OPENFGA_MODEL_ID = "01HWBBMZTT7F1M97DVXQK4Z7J3";
diff --git a/tests/helpers/index.ts b/tests/helpers/index.ts
index 3a37f229..9efdae12 100644
--- a/tests/helpers/index.ts
+++ b/tests/helpers/index.ts
@@ -1,2 +1,2 @@
-export { getNocks } from "./nocks";
-export { baseConfig, defaultConfiguration } from "./default-config";
+export { getNocks } from "./nocks.js";
+export { baseConfig, defaultConfiguration } from "./default-config.js";
diff --git a/tests/helpers/nocks.ts b/tests/helpers/nocks.ts
index 3da81711..e60d9ef0 100644
--- a/tests/helpers/nocks.ts
+++ b/tests/helpers/nocks.ts
@@ -27,8 +27,8 @@ import {
   TupleKey,
   TupleOperation,
   WriteAuthorizationModelRequest,
-} from "../../index";
-import { defaultConfiguration } from "./default-config";
+} from "../../index.js";
+import { defaultConfiguration } from "./default-config.js";
 
 export const getNocks = ((nock: Nock) => ({
   tokenExchange: (
diff --git a/tests/index.test.ts b/tests/index.test.ts
index b242a048..569ebfec 100644
--- a/tests/index.test.ts
+++ b/tests/index.test.ts
@@ -14,17 +14,17 @@ import {
   FgaError,
   OpenFgaApi,
   TelemetryAttribute,
-} from "../index";
-import { CallResult } from "../common";
-import { GetDefaultRetryParams } from "../configuration";
-import { AuthCredentialsConfig } from "../credentials";
+} from "../index.js";
+import { CallResult } from "../common.js";
+import { GetDefaultRetryParams } from "../configuration.js";
+import { AuthCredentialsConfig } from "../credentials/index.js";
 import {
   baseConfig,
   defaultConfiguration,
   OPENFGA_API_TOKEN_ISSUER,
   OPENFGA_CLIENT_ASSERTION_SIGNING_KEY,
-} from "./helpers/default-config";
-import { getNocks } from "./helpers/nocks";
+} from "./helpers/default-config.js";
+import { getNocks } from "./helpers/nocks.js";
 
 const nocks = getNocks(nock);
 nock.disableNetConnect();
diff --git a/tests/jest.config.js b/tests/jest.config.js
index a6f6aa57..f4e3c126 100644
--- a/tests/jest.config.js
+++ b/tests/jest.config.js
@@ -6,6 +6,9 @@ module.exports = {
     "^.+\\.ts$": ["ts-jest", { tsconfig: "tests/tsconfig.spec.json" }],
   },
   moduleFileExtensions: ["js", "d.ts", "ts", "json"],
+  moduleNameMapper: {
+    "^(\\.{1,2}/.*)\\.js$": "$1",
+  },
   setupFilesAfterEnv: ["./tests/setup.ts"],
   collectCoverage: true,
   coverageReporters: ["text", "cobertura", "lcov"],
diff --git a/tests/streaming.test.ts b/tests/streaming.test.ts
index aaa39092..fc4b62f0 100644
--- a/tests/streaming.test.ts
+++ b/tests/streaming.test.ts
@@ -13,7 +13,7 @@
 
 import { Readable } from "node:stream";
 import { EventEmitter } from "node:events";
-import { parseNDJSONStream } from "../streaming";
+import { parseNDJSONStream } from "../streaming.js";
 
 describe("Streaming Utilities", () => {
   describe("parseNDJSONStream (Node.js)", () => {
diff --git a/tests/telemetry/attributes.test.ts b/tests/telemetry/attributes.test.ts
index b0df321f..2e10828c 100644
--- a/tests/telemetry/attributes.test.ts
+++ b/tests/telemetry/attributes.test.ts
@@ -1,4 +1,4 @@
-import { TelemetryAttribute, TelemetryAttributes } from "../../telemetry/attributes";
+import { TelemetryAttribute, TelemetryAttributes } from "../../telemetry/attributes.js";
 
 describe("TelemetryAttributes", () => {
 
diff --git a/tests/telemetry/configuration.test.ts b/tests/telemetry/configuration.test.ts
index 4beccb8c..b16a996d 100644
--- a/tests/telemetry/configuration.test.ts
+++ b/tests/telemetry/configuration.test.ts
@@ -1,6 +1,6 @@
-import { TelemetryConfiguration, TelemetryMetricConfig } from "../../telemetry/configuration";
-import { TelemetryAttribute } from "../../telemetry/attributes";
-import { TelemetryMetric } from "../../telemetry/metrics";
+import { TelemetryConfiguration, TelemetryMetricConfig } from "../../telemetry/configuration.js";
+import { TelemetryAttribute } from "../../telemetry/attributes.js";
+import { TelemetryMetric } from "../../telemetry/metrics.js";
 
 describe("TelemetryConfiguration", () => {
   test("should use defaults if not all metrics defined", () => {
diff --git a/tests/telemetry/counters.test.ts b/tests/telemetry/counters.test.ts
index 64ddb575..bf4cbbe0 100644
--- a/tests/telemetry/counters.test.ts
+++ b/tests/telemetry/counters.test.ts
@@ -1,4 +1,4 @@
-import { TelemetryCounters } from "../../telemetry/counters";
+import { TelemetryCounters } from "../../telemetry/counters.js";
 
 describe("TelemetryCounters", () => {
   test("should have correct counter details", () => {
diff --git a/tests/telemetry/histograms.test.ts b/tests/telemetry/histograms.test.ts
index 390ecf06..697d539a 100644
--- a/tests/telemetry/histograms.test.ts
+++ b/tests/telemetry/histograms.test.ts
@@ -1,4 +1,4 @@
-import { TelemetryHistograms } from "../../telemetry/histograms";
+import { TelemetryHistograms } from "../../telemetry/histograms.js";
 
 describe("TelemetryHistograms", () => {
   test("should have correct histogram details for request duration", () => {
diff --git a/tests/telemetry/metrics.test.ts b/tests/telemetry/metrics.test.ts
index 5fca7dc9..ade3ae0a 100644
--- a/tests/telemetry/metrics.test.ts
+++ b/tests/telemetry/metrics.test.ts
@@ -1,8 +1,8 @@
-import { MetricRecorder } from "../../telemetry/metrics";
-import { TelemetryCounters } from "../../telemetry/counters";
-import { TelemetryHistograms } from "../../telemetry/histograms";
-import { TelemetryAttributes } from "../../telemetry/attributes";
-import SdkConstants from "../../constants";
+import { MetricRecorder } from "../../telemetry/metrics.js";
+import { TelemetryCounters } from "../../telemetry/counters.js";
+import { TelemetryHistograms } from "../../telemetry/histograms.js";
+import { TelemetryAttributes } from "../../telemetry/attributes.js";
+import SdkConstants from "../../constants/index.js";
 import { metrics } from "@opentelemetry/api";
 
 jest.mock("@opentelemetry/api", () => ({
diff --git a/tests/validation.test.ts b/tests/validation.test.ts
index 96e3ddc2..6ac149a0 100644
--- a/tests/validation.test.ts
+++ b/tests/validation.test.ts
@@ -1,4 +1,4 @@
-import { isWellFormedUlidString } from "../validation";
+import { isWellFormedUlidString } from "../validation.js";
 
 describe("validation.ts", () => {
   describe("isWellFormedUlidString", () => {
diff --git a/tsconfig.esm.json b/tsconfig.esm.json
new file mode 100644
index 00000000..ea3840e4
--- /dev/null
+++ b/tsconfig.esm.json
@@ -0,0 +1,10 @@
+{
+  "extends": "./tsconfig.json",
+  "compilerOptions": {
+    "module": "es2020",
+    "moduleResolution": "bundler",
+    "outDir": "dist/esm",
+    "declaration": false,
+    "declarationDir": null
+  }
+}
diff --git a/tsconfig.json b/tsconfig.json
index 193774f6..e41593e6 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -5,7 +5,8 @@
     "module": "commonjs",
     "noImplicitAny": true,
     "strict": true,
-    "outDir": "dist",
+    "declarationDir": "dist",
+    "outDir": "dist/cjs",
     "rootDir": ".",
     "typeRoots": [
       "node_modules/@types"
diff --git a/utils/generate-random-id.ts b/utils/generate-random-id.ts
index ba88ec0a..64e37d51 100644
--- a/utils/generate-random-id.ts
+++ b/utils/generate-random-id.ts
@@ -3,9 +3,10 @@ import { randomUUID, randomBytes } from "crypto";
 /**
  * Generates a random ID
  *
- * Note: May not return a valid value on older browsers - we're fine with this for now
+ * Note: May not return a secure random value.
+ *       We're fine with this, as this is just used to identify requests.
  */
-export function generateRandomId(): string | undefined {
+export function generateRandomId(): string {
   if (typeof randomUUID === "function") {
     return randomUUID();
   }
@@ -15,10 +16,15 @@ export function generateRandomId(): string | undefined {
     return randomBytes(20).toString("hex");
   }
 
-  // For older browsers
-  return;
+  // Fallback for older browsers and runtimes without crypto support
+  const chars = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
+  let result = "";
+  for (let i = 0; i < 20; i++) {
+    result += chars.charAt(Math.floor(Math.random() * chars.length));
+  }
+  return result;
 }
 
 export function generateRandomIdWithNonUniqueFallback(): string {
-  return generateRandomId() || "00000000-0000-0000-0000-000000000000";
+  return generateRandomId();
 }
diff --git a/utils/index.ts b/utils/index.ts
index 441a9a1a..df039048 100644
--- a/utils/index.ts
+++ b/utils/index.ts
@@ -1,5 +1,2 @@
-export * from "./assert-never";
-export * from "./chunk-array";
-export * from "./generate-random-id";
-export * from "./set-header-if-not-set";
-export * from "./set-not-enumerable-property";
+export * from "./utils-lite/index.js";
+export * from "./generate-random-id.js";
diff --git a/utils/assert-never.ts b/utils/utils-lite/assert-never.ts
similarity index 100%
rename from utils/assert-never.ts
rename to utils/utils-lite/assert-never.ts
diff --git a/utils/utils-lite/async-pool.ts b/utils/utils-lite/async-pool.ts
new file mode 100644
index 00000000..df28ab35
--- /dev/null
+++ b/utils/utils-lite/async-pool.ts
@@ -0,0 +1,69 @@
+/**
+ * Async concurrency pool.
+ *
+ * Based on tiny-async-pool by Rafael Xavier de Souza, licensed under MIT.
+ * https://github.com/rxaviers/async-pool
+ *
+ * Original license from https://github.com/rxaviers/async-pool/blob/master/LICENSE-MIT:
+ *
+ *   Copyright (c) 2017 Rafael Xavier de Souza http://rafael.xavier.blog.br
+ *
+ *   Permission is hereby granted, free of charge, to any person
+ *   obtaining a copy of this software and associated documentation
+ *   files (the "Software"), to deal in the Software without
+ *   restriction, including without limitation the rights to use,
+ *   copy, modify, merge, publish, distribute, sublicense, and/or sell
+ *   copies of the Software, and to permit persons to whom the
+ *   Software is furnished to do so, subject to the following
+ *   conditions:
+ *
+ *   The above copyright notice and this permission notice shall be
+ *   included in all copies or substantial portions of the Software.
+ *
+ *   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ *   EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+ *   OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ *   NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+ *   HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ *   WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ *   FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ *   OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+/**
+ * Runs async functions in a limited concurrency pool.
+ * Yields results as they complete, in order of input.
+ * Rejects immediately if any promise rejects.
+ *
+ * @param concurrency - Maximum number of concurrent executions (>= 1)
+ * @param iterable - Input items to process
+ * @param iteratorFn - Async function to apply to each item
+ */
+export async function* asyncPool<IN, OUT>(
+  concurrency: number,
+  iterable: Iterable<IN>,
+  iteratorFn: (item: IN) => Promise<OUT>,
+): AsyncGenerator<OUT> {
+  // eslint-disable-next-line @typescript-eslint/no-explicit-any
+  const executing = new Set<Promise<any>>();
+
+  async function consume(): Promise<OUT> {
+    const [promise, value] = await Promise.race(executing);
+    executing.delete(promise);
+    return value;
+  }
+
+  for (const item of iterable) {
+    // eslint-disable-next-line @typescript-eslint/no-explicit-any
+    let promise: Promise<any>;
+    promise = (async () => iteratorFn(item))()
+      .then((value): [Promise<unknown>, OUT] => [promise, value]);
+    executing.add(promise);
+    if (executing.size >= concurrency) {
+      yield await consume();
+    }
+  }
+  while (executing.size) {
+    yield await consume();
+  }
+}
diff --git a/utils/chunk-array.ts b/utils/utils-lite/chunk-array.ts
similarity index 100%
rename from utils/chunk-array.ts
rename to utils/utils-lite/chunk-array.ts
diff --git a/utils/utils-lite/index.ts b/utils/utils-lite/index.ts
new file mode 100644
index 00000000..668a40d9
--- /dev/null
+++ b/utils/utils-lite/index.ts
@@ -0,0 +1,5 @@
+export * from "./assert-never.js";
+export * from "./async-pool.js";
+export * from "./chunk-array.js";
+export * from "./set-header-if-not-set.js";
+export * from "./set-not-enumerable-property.js";
diff --git a/utils/set-header-if-not-set.ts b/utils/utils-lite/set-header-if-not-set.ts
similarity index 100%
rename from utils/set-header-if-not-set.ts
rename to utils/utils-lite/set-header-if-not-set.ts
diff --git a/utils/set-not-enumerable-property.ts b/utils/utils-lite/set-not-enumerable-property.ts
similarity index 100%
rename from utils/set-not-enumerable-property.ts
rename to utils/utils-lite/set-not-enumerable-property.ts
diff --git a/validation.ts b/validation.ts
index 33d75b21..91ca4535 100644
--- a/validation.ts
+++ b/validation.ts
@@ -1,4 +1,4 @@
-import { FgaRequiredParamError } from "./errors";
+import { FgaRequiredParamError } from "./errors.js";
 
 /**
  *