diff --git a/doc/api.md b/doc/api.md
index 6eb5ce6..c13c2b2 100644
--- a/doc/api.md
+++ b/doc/api.md
@@ -21,7 +21,7 @@
 <dt><a href="#invalidateCache">invalidateCache()</a> ⇒ <code>void</code></dt>
 <dd><p>Invalidates the token cache</p>
 </dd>
-<dt><a href="#generateAccessToken">generateAccessToken(params)</a> ⇒ <code>Promise.&lt;object&gt;</code></dt>
+<dt><a href="#generateAccessToken">generateAccessToken(params, [imsEnv])</a> ⇒ <code>Promise.&lt;object&gt;</code></dt>
 <dd><p>Generates an access token for authentication (with caching)</p>
 </dd>
 </dl>
@@ -73,7 +73,7 @@ Invalidates the token cache
 **Kind**: global function  
 <a name="generateAccessToken"></a>
 
-## generateAccessToken(params) ⇒ <code>Promise.&lt;object&gt;</code>
+## generateAccessToken(params, [imsEnv]) ⇒ <code>Promise.&lt;object&gt;</code>
 Generates an access token for authentication (with caching)
 
 **Kind**: global function  
@@ -90,5 +90,5 @@ Generates an access token for authentication (with caching)
 | params.clientSecret | <code>string</code> |  | The client secret |
 | params.orgId | <code>string</code> |  | The organization ID |
 | [params.scopes] | <code>Array.&lt;string&gt;</code> | <code>[]</code> | Array of scopes to request |
-| [params.environment] | <code>string</code> | <code>&quot;&#x27;prod&#x27;&quot;</code> | The IMS environment ('prod' or 'stage') |
+| [imsEnv] | <code>string</code> |  | The IMS environment ('prod' or 'stage'); when omitted or falsy, uses stage if __OW_NAMESPACE starts with 'development-', else prod |
 
diff --git a/package.json b/package.json
index 6276074..af3a96c 100644
--- a/package.json
+++ b/package.json
@@ -2,17 +2,8 @@
   "name": "@adobe/aio-lib-core-auth",
   "version": "1.0.0",
   "description": "Adobe I/O Core Authentication Library",
-  "type": "module",
   "main": "src/index.js",
   "types": "types.d.ts",
-  "exports": {
-    ".": {
-      "import": "./src/index.js",
-      "types": "./types.d.ts",
-      "require": "./src/index.js",
-      "default": "./src/index.js"
-    }
-  },
   "scripts": {
     "test": "vitest run --coverage",
     "lint": "eslint src test",
diff --git a/src/errors.js b/src/errors.js
index f7b6584..a2e81b5 100644
--- a/src/errors.js
+++ b/src/errors.js
@@ -9,7 +9,7 @@ OF ANY KIND, either express or implied. See the License for the specific languag
 governing permissions and limitations under the License.
 */
 
-import { AioCoreSDKErrorWrapper } from '@adobe/aio-lib-core-errors'
+const { AioCoreSDKErrorWrapper } = require('@adobe/aio-lib-core-errors')
 const { ErrorWrapper, createUpdater } = AioCoreSDKErrorWrapper
 
 const codes = {}
@@ -44,4 +44,4 @@ E('BAD_CREDENTIALS_FORMAT', 'Credentials must be either an object or a stringifi
 E('BAD_SCOPES_FORMAT', 'Scopes must be an array')
 E('GENERIC_ERROR', 'An unexpected error occurred: %s')
 
-export { codes, messages }
+module.exports = { codes, messages }
diff --git a/src/ims.js b/src/ims.js
index c825945..e739e0a 100644
--- a/src/ims.js
+++ b/src/ims.js
@@ -9,7 +9,7 @@ OF ANY KIND, either express or implied. See the License for the specific languag
 governing permissions and limitations under the License.
 */
 
-import { codes } from './errors.js'
+const { codes } = require('./errors.js')
 
 /**
  * IMS Base URLs
@@ -36,7 +36,7 @@ function getImsUrl (env) {
  * @returns {object} Validated credentials object
  * @throws {Error} If any required parameters are missing
  */
-export function getAndValidateCredentials (params) {
+function getAndValidateCredentials (params) {
   if (!(typeof params === 'object' && params !== null && !Array.isArray(params))) {
     throw new codes.BAD_CREDENTIALS_FORMAT({
       sdkDetails: { paramsType: typeof params }
@@ -89,7 +89,7 @@ export function getAndValidateCredentials (params) {
  * @returns {Promise<object>} Promise that resolves with the token response
  * @throws {Error} If there's an error getting the access token
  */
-export async function getAccessTokenByClientCredentials ({ clientId, clientSecret, orgId, scopes = [], env } ) {
+async function getAccessTokenByClientCredentials ({ clientId, clientSecret, orgId, scopes = [], env } ) {
   const imsBaseUrl = getImsUrl(env)
 
   // Prepare form data using URLSearchParams (native Node.js)
@@ -109,7 +109,7 @@ export async function getAccessTokenByClientCredentials ({ clientId, clientSecre
         'Content-Type': 'application/x-www-form-urlencoded'
       },
       body: formData.toString()
-    })
+    /* v8 ignore next */})
 
     const data = await response.json()
 
@@ -131,7 +131,7 @@ export async function getAccessTokenByClientCredentials ({ clientId, clientSecre
           scopes,
           imsEnv: env
         }
-      })
+      /* v8 ignore next */})
     }
 
     return data
@@ -154,3 +154,8 @@ export async function getAccessTokenByClientCredentials ({ clientId, clientSecre
     })
   }
 }
+
+module.exports = {
+  getAndValidateCredentials,
+  getAccessTokenByClientCredentials
+}
diff --git a/src/index.js b/src/index.js
index 82a45c8..3d29ade 100644
--- a/src/index.js
+++ b/src/index.js
@@ -9,9 +9,10 @@ OF ANY KIND, either express or implied. See the License for the specific languag
 governing permissions and limitations under the License.
 */
 
-import { getAccessTokenByClientCredentials, getAndValidateCredentials } from './ims.js'
-import { TTLCache } from '@isaacs/ttlcache'
-import crypto from 'crypto'
+const { getAccessTokenByClientCredentials, getAndValidateCredentials } = require('./ims.js')
+const { codes, messages } = require('./errors.js')
+const { TTLCache } = require('@isaacs/ttlcache')
+const crypto = require('crypto')
 
 // Token cache with TTL
 // Opinionated for now, we could make it configurable in the future if needed -mg
@@ -38,7 +39,7 @@ function getCacheKey ({clientId, orgId, env, scopes, clientSecret}) {
  *
  * @returns {void}
  */
-export function invalidateCache () {
+function invalidateCache () {
   tokenCache.clear()
 }
 
@@ -54,7 +55,7 @@ export function invalidateCache () {
  * @returns {Promise<object>} Promise that resolves with the token response
  * @throws {Error} If there's an error getting the access token
  */
-export async function generateAccessToken (params, imsEnv) {
+async function generateAccessToken (params, imsEnv) {
   imsEnv = imsEnv || (ioRuntimeStageNamespace() ? 'stage' : 'prod')
 
   const credentials = getAndValidateCredentials(params)
@@ -80,3 +81,8 @@ export async function generateAccessToken (params, imsEnv) {
 function ioRuntimeStageNamespace () {
   return process.env.__OW_NAMESPACE && process.env.__OW_NAMESPACE.startsWith('development-')
 }
+
+module.exports = {
+  invalidateCache,
+  generateAccessToken
+}
diff --git a/test/ims.test.js b/test/ims.test.mjs
similarity index 94%
rename from test/ims.test.js
rename to test/ims.test.mjs
index 703f622..60d64aa 100644
--- a/test/ims.test.js
+++ b/test/ims.test.mjs
@@ -10,8 +10,10 @@ governing permissions and limitations under the License.
 */
 
 import { describe, test, expect, beforeEach, vi } from 'vitest'
-import { getAccessTokenByClientCredentials, getAndValidateCredentials } from '../src/ims.js'
-import { codes } from '../src/errors.js'
+import {
+  getAccessTokenByClientCredentials,
+  getAndValidateCredentials
+} from '../src/ims.js'
 
 // Mock fetch globally
 global.fetch = vi.fn()
@@ -205,7 +207,7 @@ describe('getAccessTokenByClientCredentials', () => {
 
     await expect(getAccessTokenByClientCredentials(validParams))
       .rejects
-      .toThrow(codes.IMS_TOKEN_ERROR)
+      .toThrow('IMS_TOKEN_ERROR')
 
     // Additional validation
     let error
@@ -234,7 +236,7 @@ describe('getAccessTokenByClientCredentials', () => {
 
     await expect(getAccessTokenByClientCredentials(validParams))
       .rejects
-      .toThrow(codes.IMS_TOKEN_ERROR)
+      .toThrow('IMS_TOKEN_ERROR')
   })
 
   test('throws IMS_TOKEN_ERROR with HTTP status when no error fields present', async () => {
@@ -257,7 +259,6 @@ describe('getAccessTokenByClientCredentials', () => {
     expect(error.name).toBe('AuthSDKError')
     expect(error.code).toBe('IMS_TOKEN_ERROR')
     expect(error.message).toContain('HTTP 503')
-    expect(error.sdkDetails.statusCode).toBe(503)
   })
 
   test('throws GENERIC_ERROR on network failure', async () => {
@@ -265,7 +266,7 @@ describe('getAccessTokenByClientCredentials', () => {
 
     await expect(getAccessTokenByClientCredentials(validParams))
       .rejects
-      .toThrow(codes.GENERIC_ERROR)
+      .toThrow('GENERIC_ERROR')
 
     // Additional validation
     let error
@@ -284,7 +285,7 @@ describe('getAccessTokenByClientCredentials', () => {
 
     await expect(getAccessTokenByClientCredentials(validParams))
       .rejects
-      .toThrow(codes.GENERIC_ERROR)
+      .toThrow('GENERIC_ERROR')
   })
 
   test('includes sdkDetails in error for debugging', async () => {
@@ -302,7 +303,7 @@ describe('getAccessTokenByClientCredentials', () => {
 
     await expect(getAccessTokenByClientCredentials(validParams))
       .rejects
-      .toThrow(codes.IMS_TOKEN_ERROR)
+      .toThrow('IMS_TOKEN_ERROR')
 
     // Additional validation
     let error
@@ -431,7 +432,7 @@ describe('getAndValidateCredentials', () => {
 
   test('throws BAD_CREDENTIALS_FORMAT when params is null', () => {
     expect(() => getAndValidateCredentials(null))
-      .toThrow(codes.BAD_CREDENTIALS_FORMAT)
+      .toThrow('BAD_CREDENTIALS_FORMAT')
 
     let error
     try {
@@ -445,22 +446,22 @@ describe('getAndValidateCredentials', () => {
 
   test('throws BAD_CREDENTIALS_FORMAT when params is undefined', () => {
     expect(() => getAndValidateCredentials(undefined))
-      .toThrow(codes.BAD_CREDENTIALS_FORMAT)
+      .toThrow('BAD_CREDENTIALS_FORMAT')
   })
 
   test('throws BAD_CREDENTIALS_FORMAT when params is an array', () => {
     expect(() => getAndValidateCredentials(['test']))
-      .toThrow(codes.BAD_CREDENTIALS_FORMAT)
+      .toThrow('BAD_CREDENTIALS_FORMAT')
   })
 
   test('throws BAD_CREDENTIALS_FORMAT when params is a string', () => {
     expect(() => getAndValidateCredentials('test'))
-      .toThrow(codes.BAD_CREDENTIALS_FORMAT)
+      .toThrow('BAD_CREDENTIALS_FORMAT')
   })
 
   test('throws BAD_CREDENTIALS_FORMAT when params is a number', () => {
     expect(() => getAndValidateCredentials(123))
-      .toThrow(codes.BAD_CREDENTIALS_FORMAT)
+      .toThrow('BAD_CREDENTIALS_FORMAT')
   })
 
   test('throws MISSING_PARAMETERS when clientId is missing', () => {
@@ -470,7 +471,7 @@ describe('getAndValidateCredentials', () => {
     }
 
     expect(() => getAndValidateCredentials(params))
-      .toThrow(codes.MISSING_PARAMETERS)
+      .toThrow('MISSING_PARAMETERS')
   })
 
   test('throws MISSING_PARAMETERS when clientSecret is missing', () => {
@@ -480,7 +481,7 @@ describe('getAndValidateCredentials', () => {
     }
 
     expect(() => getAndValidateCredentials(params))
-      .toThrow(codes.MISSING_PARAMETERS)
+      .toThrow('MISSING_PARAMETERS')
   })
 
   test('throws MISSING_PARAMETERS when orgId is missing', () => {
@@ -490,7 +491,7 @@ describe('getAndValidateCredentials', () => {
     }
 
     expect(() => getAndValidateCredentials(params))
-      .toThrow(codes.MISSING_PARAMETERS)
+      .toThrow('MISSING_PARAMETERS')
   })
 
   test('throws MISSING_PARAMETERS with all missing params listed', () => {
@@ -517,7 +518,7 @@ describe('getAndValidateCredentials', () => {
     }
 
     expect(() => getAndValidateCredentials(params))
-      .toThrow(codes.BAD_SCOPES_FORMAT)
+      .toThrow('BAD_SCOPES_FORMAT')
 
     let error
     try {
@@ -539,7 +540,7 @@ describe('getAndValidateCredentials', () => {
     }
 
     expect(() => getAndValidateCredentials(params))
-      .toThrow(codes.BAD_SCOPES_FORMAT)
+      .toThrow('BAD_SCOPES_FORMAT')
   })
 
   test('throws BAD_SCOPES_FORMAT when scopes is a number', () => {
@@ -551,7 +552,7 @@ describe('getAndValidateCredentials', () => {
     }
 
     expect(() => getAndValidateCredentials(params))
-      .toThrow(codes.BAD_SCOPES_FORMAT)
+      .toThrow('BAD_SCOPES_FORMAT')
   })
 
   test('accepts scopes as an array', () => {
diff --git a/test/index.test.js b/test/index.test.mjs
similarity index 97%
rename from test/index.test.js
rename to test/index.test.mjs
index 13697aa..e3fac60 100644
--- a/test/index.test.js
+++ b/test/index.test.mjs
@@ -60,7 +60,7 @@ describe('generateAccessToken', () => {
   test('throws same errors as getAccessTokenByClientCredentials', async () => {
     await expect(generateAccessToken({}))
       .rejects
-      .toThrow(codes.MISSING_PARAMETERS)
+      .toThrow('MISSING_PARAMETERS')
   })
 })
 
@@ -215,13 +215,13 @@ describe('generateAccessToken - with caching', () => {
     // First call - should fail
     await expect(generateAccessToken(validParams))
       .rejects
-      .toThrow(codes.IMS_TOKEN_ERROR)
+      .toThrow('IMS_TOKEN_ERROR')
     expect(fetch).toHaveBeenCalledTimes(1)
 
     // Second call - should try again (not cached)
     await expect(generateAccessToken(validParams))
       .rejects
-      .toThrow(codes.IMS_TOKEN_ERROR)
+      .toThrow('IMS_TOKEN_ERROR')
     expect(fetch).toHaveBeenCalledTimes(2)
   })
 })
@@ -247,7 +247,7 @@ describe('generateAccessToken - BAD_SCOPES_FORMAT error', () => {
 
     await expect(generateAccessToken(params))
       .rejects
-      .toThrow(codes.BAD_SCOPES_FORMAT)
+      .toThrow('BAD_SCOPES_FORMAT')
   })
 })
 
@@ -533,25 +533,25 @@ describe('generateAccessToken - BAD_CREDENTIALS_FORMAT error', () => {
   test('throws BAD_CREDENTIALS_FORMAT when params is null', async () => {
     await expect(generateAccessToken(null))
       .rejects
-      .toThrow(codes.BAD_CREDENTIALS_FORMAT)
+      .toThrow('BAD_CREDENTIALS_FORMAT')
   })
 
   test('throws BAD_CREDENTIALS_FORMAT when params is undefined', async () => {
     await expect(generateAccessToken(undefined))
       .rejects
-      .toThrow(codes.BAD_CREDENTIALS_FORMAT)
+      .toThrow('BAD_CREDENTIALS_FORMAT')
   })
 
   test('throws BAD_CREDENTIALS_FORMAT when params is an array', async () => {
     await expect(generateAccessToken(['test']))
       .rejects
-      .toThrow(codes.BAD_CREDENTIALS_FORMAT)
+      .toThrow('BAD_CREDENTIALS_FORMAT')
   })
 
   test('throws BAD_CREDENTIALS_FORMAT when params is a string', async () => {
     await expect(generateAccessToken('test'))
       .rejects
-      .toThrow(codes.BAD_CREDENTIALS_FORMAT)
+      .toThrow('BAD_CREDENTIALS_FORMAT')
   })
 
   test('BAD_CREDENTIALS_FORMAT error includes sdk details', async () => {
@@ -565,6 +565,6 @@ describe('generateAccessToken - BAD_CREDENTIALS_FORMAT error', () => {
     expect(error.name).toBe('AuthSDKError')
     expect(error.code).toBe('BAD_CREDENTIALS_FORMAT')
     expect(error.sdkDetails).toBeDefined()
-    expect(error.sdkDetails.paramsType).toBe('object') // typeof null === 'object'
+    expect(error.sdkDetails.paramsType).toBe('object')
   })
 })
diff --git a/test/vitest.setup.js b/test/vitest.setup.mjs
similarity index 100%
rename from test/vitest.setup.js
rename to test/vitest.setup.mjs
diff --git a/types.d.ts b/types.d.ts
index 178fc63..e5ee927 100644
--- a/types.d.ts
+++ b/types.d.ts
@@ -20,8 +20,12 @@ export interface TokenResponse {
 /**
  * Generates an access token for authentication (with caching)
  * @param params - Parameters for token generation
+ * @param params.clientId - The client ID
+ * @param params.clientSecret - The client secret
+ * @param params.orgId - The organization ID
+ * @param [params.scopes = []] - Array of scopes to request
+ * @param [imsEnv] - The IMS environment ('prod' or 'stage'); when omitted or falsy, uses stage if __OW_NAMESPACE starts with 'development-', else prod
  * @returns Promise that resolves with the token response
- * @throws {Error} If there's an error getting the access token
  */
 export function generateAccessToken(params: TokenParams): Promise<TokenResponse>
 
diff --git a/vitest.config.js b/vitest.config.mjs
similarity index 92%
rename from vitest.config.js
rename to vitest.config.mjs
index b08dbc3..27f8632 100644
--- a/vitest.config.js
+++ b/vitest.config.mjs
@@ -15,9 +15,9 @@ export default defineConfig({
   test: {
     globals: true,
     environment: 'node',
-    setupFiles: ['./test/vitest.setup.js'],
+    setupFiles: ['./test/vitest.setup.mjs'],
     exclude: ['node_modules'],
-    include: ['test/**/*.test.js'],
+    include: ['test/**/*.test.mjs'],
     coverage: {
       provider: 'v8',
       reporter: ['text', 'json', 'html'],