diff --git a/projects/angular-server-side-configuration/builders/ngsscbuild/index.ts b/projects/angular-server-side-configuration/builders/ngsscbuild/index.cts
similarity index 97%
rename from projects/angular-server-side-configuration/builders/ngsscbuild/index.ts
rename to projects/angular-server-side-configuration/builders/ngsscbuild/index.cts
index c5897f0..b60ff48 100644
--- a/projects/angular-server-side-configuration/builders/ngsscbuild/index.ts
+++ b/projects/angular-server-side-configuration/builders/ngsscbuild/index.cts
@@ -9,9 +9,9 @@ import type { ApplicationBuilderOptions } from '@angular/build';
 import type { json, JsonObject } from '@angular-devkit/core';
 import type { Ngssc } from 'angular-server-side-configuration';
 import * as glob from 'glob';
-import type { Schema } from './schema';
-import { VariableDetector } from './variable-detector';
-import type { NgsscContext } from './ngssc-context';
+import type { Schema } from './schema.cjs';
+import { VariableDetector } from './variable-detector.cjs';
+import type { NgsscContext } from './ngssc-context.cjs';
 
 export type NgsscBuildSchema = Schema;
 type ApplicationBuilderVariant = undefined | 'browser-only' | 'server';
diff --git a/projects/angular-server-side-configuration/builders/ngsscbuild/index.spec.ts b/projects/angular-server-side-configuration/builders/ngsscbuild/index.spec.ts
index 5926850..48965f1 100644
--- a/projects/angular-server-side-configuration/builders/ngsscbuild/index.spec.ts
+++ b/projects/angular-server-side-configuration/builders/ngsscbuild/index.spec.ts
@@ -1,8 +1,8 @@
 import type { Ngssc } from 'angular-server-side-configuration';
 
 import { describeBuilder } from '../../../../modules/testing/builder/src';
-import { Schema } from './schema';
-import { ngsscBuild } from './index';
+import { Schema } from './schema.cjs';
+import { ngsscBuild } from './index.cjs';
 
 const APPLICATION_BUILDER_INFO = Object.freeze({
   name: 'angular-server-side-configuration:ngsscbuild',
diff --git a/projects/angular-server-side-configuration/builders/ngsscbuild/ngssc-context.ts b/projects/angular-server-side-configuration/builders/ngsscbuild/ngssc-context.cts
similarity index 100%
rename from projects/angular-server-side-configuration/builders/ngsscbuild/ngssc-context.ts
rename to projects/angular-server-side-configuration/builders/ngsscbuild/ngssc-context.cts
diff --git a/projects/angular-server-side-configuration/builders/ngsscbuild/schema.ts b/projects/angular-server-side-configuration/builders/ngsscbuild/schema.cts
similarity index 100%
rename from projects/angular-server-side-configuration/builders/ngsscbuild/schema.ts
rename to projects/angular-server-side-configuration/builders/ngsscbuild/schema.cts
diff --git a/projects/angular-server-side-configuration/builders/ngsscbuild/variable-detector.ts b/projects/angular-server-side-configuration/builders/ngsscbuild/variable-detector.cts
similarity index 97%
rename from projects/angular-server-side-configuration/builders/ngsscbuild/variable-detector.ts
rename to projects/angular-server-side-configuration/builders/ngsscbuild/variable-detector.cts
index df1977b..b42baae 100644
--- a/projects/angular-server-side-configuration/builders/ngsscbuild/variable-detector.ts
+++ b/projects/angular-server-side-configuration/builders/ngsscbuild/variable-detector.cts
@@ -11,7 +11,7 @@ import {
 } from 'typescript';
 import type { Variant } from 'angular-server-side-configuration';
 import type { logging } from '@angular-devkit/core';
-import type { NgsscContext } from './ngssc-context';
+import type { NgsscContext } from './ngssc-context.cjs';
 
 /** Detect environment variables in given file. */
 export class VariableDetector {
diff --git a/projects/angular-server-side-configuration/builders/ngsscbuild/variable-detector.spec.ts b/projects/angular-server-side-configuration/builders/ngsscbuild/variable-detector.spec.ts
index 68e5413..bdc3d35 100644
--- a/projects/angular-server-side-configuration/builders/ngsscbuild/variable-detector.spec.ts
+++ b/projects/angular-server-side-configuration/builders/ngsscbuild/variable-detector.spec.ts
@@ -1,4 +1,4 @@
-import { VariableDetector } from './variable-detector';
+import { VariableDetector } from './variable-detector.cjs';
 
 describe('VariableDetector', () => {
   const expectedEnvVariables = [
diff --git a/projects/angular-server-side-configuration/builders/tsconfig.json b/projects/angular-server-side-configuration/builders/tsconfig.json
index 2170681..0083552 100644
--- a/projects/angular-server-side-configuration/builders/tsconfig.json
+++ b/projects/angular-server-side-configuration/builders/tsconfig.json
@@ -4,5 +4,6 @@
     "outDir": "../../../dist/angular-server-side-configuration/builders",
     "rootDir": "."
   },
+  "include": ["**/*.cts"],
   "exclude": ["**/files/**/*", "**/*.spec.ts"]
 }
diff --git a/projects/angular-server-side-configuration/schematics/collection.json b/projects/angular-server-side-configuration/schematics/collection.json
index d09b609..0fb9429 100644
--- a/projects/angular-server-side-configuration/schematics/collection.json
+++ b/projects/angular-server-side-configuration/schematics/collection.json
@@ -3,7 +3,7 @@
   "schematics": {
     "ng-add": {
       "description": "Adds Angular Material to the application without affecting any templates",
-      "factory": "./ng-add/index#ngAdd",
+      "factory": "./ng-add/index.cts#ngAdd",
       "schema": "./ng-add/schema.json",
       "aliases": ["install"]
     }
diff --git a/projects/angular-server-side-configuration/schematics/migration.json b/projects/angular-server-side-configuration/schematics/migration.json
index d7b4348..cdbaf83 100644
--- a/projects/angular-server-side-configuration/schematics/migration.json
+++ b/projects/angular-server-side-configuration/schematics/migration.json
@@ -4,17 +4,17 @@
     "migration-v15": {
       "version": "15-next",
       "description": "Updates angular-server-side-configuration to v15",
-      "factory": "./ng-update/index#updateToV15"
+      "factory": "./ng-update/index.cts#updateToV15"
     },
     "migration-v17": {
       "version": "17-next",
       "description": "Updates angular-server-side-configuration to v17",
-      "factory": "./ng-update/index#updateToV17"
+      "factory": "./ng-update/index.cts#updateToV17"
     },
     "dockerfile": {
       "version": "22.0.0",
       "description": "Updates the download url for ngssc",
-      "factory": "./ng-update/index#dockerfile"
+      "factory": "./ng-update/index.cts#dockerfile"
     }
   }
 }
\ No newline at end of file
diff --git a/projects/angular-server-side-configuration/schematics/ng-add/index.ts b/projects/angular-server-side-configuration/schematics/ng-add/index.cts
similarity index 99%
rename from projects/angular-server-side-configuration/schematics/ng-add/index.ts
rename to projects/angular-server-side-configuration/schematics/ng-add/index.cts
index 2b802b8..0452c2c 100644
--- a/projects/angular-server-side-configuration/schematics/ng-add/index.ts
+++ b/projects/angular-server-side-configuration/schematics/ng-add/index.cts
@@ -8,7 +8,7 @@ import {
 } from '@angular-devkit/schematics';
 import { InsertChange } from '@schematics/angular/utility/change';
 import { getWorkspace, updateWorkspace } from '@schematics/angular/utility/workspace';
-import type { Schema } from './schema';
+import type { Schema } from './schema.cjs';
 
 export function ngAdd(options: Schema): Rule {
   return chain([
diff --git a/projects/angular-server-side-configuration/schematics/ng-add/schema.ts b/projects/angular-server-side-configuration/schematics/ng-add/schema.cts
similarity index 100%
rename from projects/angular-server-side-configuration/schematics/ng-add/schema.ts
rename to projects/angular-server-side-configuration/schematics/ng-add/schema.cts
diff --git a/projects/angular-server-side-configuration/schematics/ng-update/index.ts b/projects/angular-server-side-configuration/schematics/ng-update/index.cts
similarity index 100%
rename from projects/angular-server-side-configuration/schematics/ng-update/index.ts
rename to projects/angular-server-side-configuration/schematics/ng-update/index.cts
diff --git a/projects/angular-server-side-configuration/schematics/tsconfig.json b/projects/angular-server-side-configuration/schematics/tsconfig.json
index 03a9dd0..247bdc8 100644
--- a/projects/angular-server-side-configuration/schematics/tsconfig.json
+++ b/projects/angular-server-side-configuration/schematics/tsconfig.json
@@ -3,5 +3,6 @@
   "compilerOptions": {
     "outDir": "../../../dist/angular-server-side-configuration/schematics"
   },
+  "include": ["**/*.cts"],
   "exclude": ["**/files/**/*", "**/*.spec.ts"]
 }
diff --git a/projects/angular-server-side-configuration/src/glob-to-regexp.spec.ts b/projects/angular-server-side-configuration/src/glob-to-regexp.spec.ts
index 4e637a8..3d581f2 100644
--- a/projects/angular-server-side-configuration/src/glob-to-regexp.spec.ts
+++ b/projects/angular-server-side-configuration/src/glob-to-regexp.spec.ts
@@ -1,6 +1,6 @@
 // Source: https://github.com/fitzgen/glob-to-regexp/blob/master/test.js
 
-import { globToRegExp, Options } from './glob-to-regexp';
+import { globToRegExp, Options } from './glob-to-regexp.js';
 
 describe('globToRegExp', () => {
   function assertMatch(glob: string, str: string, opts?: Options) {
diff --git a/projects/angular-server-side-configuration/src/insert.spec.ts b/projects/angular-server-side-configuration/src/insert.spec.ts
index 593ae42..9f4fc1b 100644
--- a/projects/angular-server-side-configuration/src/insert.spec.ts
+++ b/projects/angular-server-side-configuration/src/insert.spec.ts
@@ -2,8 +2,8 @@ import { mkdirSync, mkdtempSync, readFileSync, writeFileSync } from 'fs';
 import { tmpdir } from 'os';
 import { join } from 'path';
 
-import { Ngssc, Variant } from './ngssc';
-import { insert } from './insert';
+import { Ngssc, Variant } from './ngssc.js';
+import { insert } from './insert.js';
 
 describe('insert', () => {
   let directory = '';
diff --git a/projects/angular-server-side-configuration/src/insert.ts b/projects/angular-server-side-configuration/src/insert.ts
index 336a003..962e228 100644
--- a/projects/angular-server-side-configuration/src/insert.ts
+++ b/projects/angular-server-side-configuration/src/insert.ts
@@ -1,8 +1,8 @@
 import { existsSync, lstatSync, readdirSync, readFileSync, writeFileSync } from 'fs';
 import { dirname, join } from 'path';
 
-import { globToRegExp } from './glob-to-regexp';
-import type { Ngssc, Variant } from './ngssc';
+import { globToRegExp } from './glob-to-regexp.js';
+import type { Ngssc, Variant } from './ngssc.js';
 
 export function insert(
   options: { dryRun?: boolean; recursive?: boolean; directory?: string } = {},
diff --git a/projects/angular-server-side-configuration/src/public-api.ts b/projects/angular-server-side-configuration/src/public-api.ts
index 22d1a08..1d8c6b4 100644
--- a/projects/angular-server-side-configuration/src/public-api.ts
+++ b/projects/angular-server-side-configuration/src/public-api.ts
@@ -1,2 +1,2 @@
-export * from './ngssc';
-export * from './insert';
+export * from './ngssc.js';
+export * from './insert.js';
diff --git a/scripts/build-lib.mts b/scripts/build-lib.mts
index 57d08b5..eb9fbae 100644
--- a/scripts/build-lib.mts
+++ b/scripts/build-lib.mts
@@ -1,6 +1,6 @@
 import { execSync } from 'child_process';
 import { lstatSync, readdirSync, readFileSync, writeFileSync } from 'fs';
-import { copyFile, mkdir, readFile } from 'fs/promises';
+import { copyFile, mkdir, readFile, writeFile } from 'fs/promises';
 import * as glob from 'glob';
 import { dirname, join, relative } from 'path';
 
@@ -27,7 +27,8 @@ async function finalizePackage() {
     const targetPath = join(targetDir, relativePath);
     console.log(` - ${relativePath}`);
     await mkdir(dirname(targetPath), { recursive: true });
-    await copyFile(file, targetPath);
+    const content = await readFile(file, 'utf8');
+    await writeFile(targetPath, content.replaceAll('.cts', '.cjs'), 'utf8');
   }
 
   const ngsscSchema: Schema = JSON.parse(