diff --git a/cli/cli-jdl.spec.ts b/cli/cli-jdl.spec.ts
index a4fe46a041ab..6ee4219d6bc7 100644
--- a/cli/cli-jdl.spec.ts
+++ b/cli/cli-jdl.spec.ts
@@ -12,7 +12,8 @@ describe('allows customizing JDL definitions', () => {
     await helpers
       .prepareTemporaryDir()
       .withFiles({
-        '.blueprint/app/index.mjs': `export const command = {
+        '.blueprint/package.json': JSON.stringify({ type: 'module' }),
+        '.blueprint/app/index.js': `export const command = {
   configs: {
     fooConfig: {
       jdl: {
diff --git a/cli/program.ts b/cli/program.ts
index 8dfc951eddf4..5faee2bdd7ba 100644
--- a/cli/program.ts
+++ b/cli/program.ts
@@ -244,7 +244,7 @@ export const buildCommands = ({
       return command;
     } catch (error) {
       try {
-        const { default: command } = await import(`./${key}.mjs`);
+        const { default: command } = await import(`./${key}.cjs`);
         return command;
       } catch {
         throw error;
diff --git a/generators/angular/__snapshots__/generator.spec.ts.snap b/generators/angular/__snapshots__/generator.spec.ts.snap
index 95ae74b991ed..223ab66fe294 100644
--- a/generators/angular/__snapshots__/generator.spec.ts.snap
+++ b/generators/angular/__snapshots__/generator.spec.ts.snap
@@ -20,7 +20,7 @@ exports[`generator - angular gateway-jwt-skipUserManagement(true)-withAdminUi(fa
   "clientRoot/angular.json": {
     "stateCleared": "modified",
   },
-  "clientRoot/eslint.config.mjs": {
+  "clientRoot/eslint.config.js": {
     "stateCleared": "modified",
   },
   "clientRoot/jest.conf.js": {
@@ -759,7 +759,7 @@ exports[`generator - angular gateway-oauth2-withAdminUi(true)-skipJhipsterDepend
   "clientRoot/angular.json": {
     "stateCleared": "modified",
   },
-  "clientRoot/eslint.config.mjs": {
+  "clientRoot/eslint.config.js": {
     "stateCleared": "modified",
   },
   "clientRoot/jest.conf.js": {
@@ -1725,7 +1725,7 @@ exports[`generator - angular microservice-jwt-skipUserManagement(false)-withAdmi
   "clientRoot/angular.json": {
     "stateCleared": "modified",
   },
-  "clientRoot/eslint.config.mjs": {
+  "clientRoot/eslint.config.js": {
     "stateCleared": "modified",
   },
   "clientRoot/jest.conf.js": {
@@ -2448,7 +2448,7 @@ exports[`generator - angular microservice-oauth2-withAdminUi(true)-skipJhipsterD
   "angular.json": {
     "stateCleared": "modified",
   },
-  "eslint.config.mjs": {
+  "eslint.config.js": {
     "stateCleared": "modified",
   },
   "jest.conf.js": {
@@ -3181,7 +3181,7 @@ exports[`generator - angular monolith-jwt-skipUserManagement(false)-withAdminUi(
   "angular.json": {
     "stateCleared": "modified",
   },
-  "eslint.config.mjs": {
+  "eslint.config.js": {
     "stateCleared": "modified",
   },
   "jest.conf.js": {
@@ -4315,7 +4315,7 @@ exports[`generator - angular monolith-oauth2-withAdminUi(false)-skipJhipsterDepe
   "angular.json": {
     "stateCleared": "modified",
   },
-  "eslint.config.mjs": {
+  "eslint.config.js": {
     "stateCleared": "modified",
   },
   "jest.conf.js": {
@@ -5024,7 +5024,7 @@ exports[`generator - angular monolith-session-skipUserManagement(true)-withAdmin
   "angular.json": {
     "stateCleared": "modified",
   },
-  "eslint.config.mjs": {
+  "eslint.config.js": {
     "stateCleared": "modified",
   },
   "jest.conf.js": {
diff --git a/generators/angular/files-angular.ts b/generators/angular/files-angular.ts
index 495bfb7abf1d..9e151a02b1a5 100644
--- a/generators/angular/files-angular.ts
+++ b/generators/angular/files-angular.ts
@@ -61,13 +61,13 @@ export const files = asWriteFilesSection({
       condition: ctx => ctx.clientBundlerExperimentalEsbuild,
       templates: [
         { sourceFile: 'angular.json.esbuild', destinationFile: 'angular.json' },
-        'proxy.config.mjs',
-        'build-plugins/define-esbuild.mjs',
+        'proxy.config.js',
+        'build-plugins/define-esbuild.js',
       ],
     }),
     clientRootTemplatesBlock({
       condition: ctx => ctx.clientBundlerExperimentalEsbuild && ctx.enableTranslation,
-      templates: ['build-plugins/i18n-esbuild.mjs'],
+      templates: ['build-plugins/i18n-esbuild.js'],
     }),
     clientSrcTemplatesBlock({
       condition: ctx => ctx.clientBundlerExperimentalEsbuild && ctx.enableTranslation,
diff --git a/generators/angular/generator.spec.ts b/generators/angular/generator.spec.ts
index 5dbb4dde17c1..6e2032aadc07 100644
--- a/generators/angular/generator.spec.ts
+++ b/generators/angular/generator.spec.ts
@@ -114,6 +114,16 @@ describe(`generator - ${clientFramework}`, () => {
         runResult.assertNoFileContent(`${clientRootDir}package.json`, /VERSION_MANAGED_BY_CLIENT_VUE/);
       });
 
+      it('should use ESM by default in package.json', () => {
+        runResult.assertFileContent(`${clientRootDir}package.json`, /"type": "module"/);
+      });
+
+      it('should not create files with .mjs extension', () => {
+        const generatedFiles = runResult.getStateSnapshot();
+        const mjsFiles = Object.keys(generatedFiles).filter(file => file.endsWith('.mjs'));
+        expect(mjsFiles).toHaveLength(0);
+      });
+
       describe('withAdminUi', () => {
         const { applicationType, withAdminUi, clientRootDir = '' } = sampleConfig;
         const clientSrcDir = `${clientRootDir}${clientRootDir ? 'src/' : CLIENT_MAIN_SRC_DIR}`;
diff --git a/generators/angular/generator.ts b/generators/angular/generator.ts
index 80a24c813ffd..532b39d7bb5d 100644
--- a/generators/angular/generator.ts
+++ b/generators/angular/generator.ts
@@ -95,7 +95,7 @@ export default class AngularGenerator extends BaseApplicationGenerator<
       applicationDefauts({ application, applicationDefaults }) {
         applicationDefaults({
           __override__: true,
-          eslintConfigFile: app => `eslint.config.${app.packageJsonType === 'module' ? 'js' : 'mjs'}`,
+          eslintConfigFile: _app => `eslint.config.js`,
           webappEnumerationsDir: app => `${app.clientSrcDir}app/entities/enumerations/`,
           angularLocaleId: app => app.nativeLanguageDefinition.angularLocale ?? defaultLanguage.angularLocale!,
         });
diff --git a/generators/angular/templates/angular.json.esbuild.ejs b/generators/angular/templates/angular.json.esbuild.ejs
index bf2ffc50c44c..0aa4a23c02f5 100644
--- a/generators/angular/templates/angular.json.esbuild.ejs
+++ b/generators/angular/templates/angular.json.esbuild.ejs
@@ -40,9 +40,9 @@
           "options": {
             "plugins": [
 <%_ if (enableTranslation) { _%>
-              "build-plugins/i18n-esbuild.mjs",
+              "build-plugins/i18n-esbuild.js",
 <%_ } _%>
-              "build-plugins/define-esbuild.mjs"
+              "build-plugins/define-esbuild.js"
             ],
             "outputPath": {
               "base": "<%= this.relativeDir(clientRootDir, clientDistDir) %>",
@@ -126,7 +126,7 @@
           "options": {
             "buildTarget": "<%= dasherizedBaseName %>:build:development",
             "open": true,
-            "proxyConfig": "proxy.config.mjs",
+            "proxyConfig": "proxy.config.js",
             "port": <%= devServerPort %>
           },
           "configurations": {
diff --git a/generators/angular/templates/build-plugins/define-esbuild.mjs.ejs b/generators/angular/templates/build-plugins/define-esbuild.js.ejs
similarity index 100%
rename from generators/angular/templates/build-plugins/define-esbuild.mjs.ejs
rename to generators/angular/templates/build-plugins/define-esbuild.js.ejs
diff --git a/generators/angular/templates/build-plugins/i18n-esbuild.mjs.ejs b/generators/angular/templates/build-plugins/i18n-esbuild.js.ejs
similarity index 100%
rename from generators/angular/templates/build-plugins/i18n-esbuild.mjs.ejs
rename to generators/angular/templates/build-plugins/i18n-esbuild.js.ejs
diff --git a/generators/angular/templates/jest.conf.js.ejs b/generators/angular/templates/jest.conf.js.ejs
index 00cc28b83065..ed9644c8e113 100644
--- a/generators/angular/templates/jest.conf.js.ejs
+++ b/generators/angular/templates/jest.conf.js.ejs
@@ -23,7 +23,7 @@ const {
 } = require('./tsconfig.json');
 
 module.exports = {
-  transformIgnorePatterns: ['node_modules/(?!.*\\.mjs$|dayjs/esm<% if (applicationTypeGateway && microfrontend) { %>|@angular-architects/module-federation-runtime<% } %>)'],
+  transformIgnorePatterns: ['node_modules/(?!.*\\.js$|dayjs/esm<% if (applicationTypeGateway && microfrontend) { %>|@angular-architects/module-federation-runtime<% } %>)'],
   resolver: 'jest-preset-angular/build/resolvers/ng-jest-resolver.js',
   globals: {
     __VERSION__: 'test',
diff --git a/generators/angular/templates/package.json.ejs b/generators/angular/templates/package.json.ejs
index e016a29352b9..fec88d0708cd 100644
--- a/generators/angular/templates/package.json.ejs
+++ b/generators/angular/templates/package.json.ejs
@@ -22,6 +22,7 @@
   "version": "0.0.1-SNAPSHOT",
   "description": "<%= projectDescription %>",
   "private": true,
+  "type": "module",
   "license": "UNLICENSED",
   "cacheDirectories": [
     "node_modules"
diff --git a/generators/angular/templates/proxy.config.mjs.ejs b/generators/angular/templates/proxy.config.js.ejs
similarity index 100%
rename from generators/angular/templates/proxy.config.mjs.ejs
rename to generators/angular/templates/proxy.config.js.ejs
diff --git a/generators/app/__snapshots__/generator.spec.ts.snap b/generators/app/__snapshots__/generator.spec.ts.snap
index 76e1d7180d6e..515248ce39c0 100644
--- a/generators/app/__snapshots__/generator.spec.ts.snap
+++ b/generators/app/__snapshots__/generator.spec.ts.snap
@@ -243,7 +243,7 @@ exports[`generator - app with default config should match snapshot 1`] = `
   "camelizedBaseName": "jhipster",
   "capitalizedBaseName": "Jhipster",
   "caret": undefined,
-  "cjsExtension": ".js",
+  "cjsExtension": ".cjs",
   "cli": undefined,
   "cliName": undefined,
   "clientBundler": "webpack",
@@ -467,7 +467,7 @@ exports[`generator - app with default config should match snapshot 1`] = `
     "com.mycompany.myapp",
   ],
   "entitySuffix": "",
-  "eslintConfigFile": "eslint.config.mjs",
+  "eslintConfigFile": "eslint.config.js",
   "feignClient": false,
   "filterEntitiesAndPropertiesForClient": [Function],
   "filterEntitiesForClient": [Function],
@@ -632,7 +632,7 @@ exports[`generator - app with default config should match snapshot 1`] = `
   "messageBrokerPulsar": false,
   "microfrontend": false,
   "microfrontends": undefined,
-  "mjsExtension": ".mjs",
+  "mjsExtension": ".js",
   "monorepository": undefined,
   "nativeLanguage": "en",
   "nativeLanguageDefinition": {
@@ -765,10 +765,7 @@ exports[`generator - app with default config should match snapshot 1`] = `
   ],
   "packageJsonNodeEngine": undefined,
   "packageJsonScripts": {},
-  "packageJsonType": "commonjs",
-  "packageJsonTypeAny": true,
-  "packageJsonTypeCommonjs": true,
-  "packageJsonTypeModule": false,
+  "packageJsonType": "module",
   "packageName": "com.mycompany.myapp",
   "pkType": undefined,
   "prettierExtensions": "md,json,yml,js,cjs,mjs,ts,cts,mts,java,html,css,scss",
@@ -895,7 +892,7 @@ exports[`generator - app with gateway should match snapshot 1`] = `
   "camelizedBaseName": "jhipster",
   "capitalizedBaseName": "Jhipster",
   "caret": undefined,
-  "cjsExtension": ".js",
+  "cjsExtension": ".cjs",
   "cli": undefined,
   "cliName": undefined,
   "clientBundler": "webpack",
@@ -1121,7 +1118,7 @@ exports[`generator - app with gateway should match snapshot 1`] = `
     "com.mycompany.myapp",
   ],
   "entitySuffix": "",
-  "eslintConfigFile": "eslint.config.mjs",
+  "eslintConfigFile": "eslint.config.js",
   "feignClient": false,
   "filterEntitiesAndPropertiesForClient": [Function],
   "filterEntitiesForClient": [Function],
@@ -1280,7 +1277,7 @@ exports[`generator - app with gateway should match snapshot 1`] = `
   "messageBrokerPulsar": false,
   "microfrontend": undefined,
   "microfrontends": undefined,
-  "mjsExtension": ".mjs",
+  "mjsExtension": ".js",
   "monorepository": undefined,
   "nativeLanguage": "en",
   "nativeLanguageDefinition": {
@@ -1413,10 +1410,7 @@ exports[`generator - app with gateway should match snapshot 1`] = `
   ],
   "packageJsonNodeEngine": undefined,
   "packageJsonScripts": {},
-  "packageJsonType": "commonjs",
-  "packageJsonTypeAny": true,
-  "packageJsonTypeCommonjs": true,
-  "packageJsonTypeModule": false,
+  "packageJsonType": "module",
   "packageName": "com.mycompany.myapp",
   "pkType": undefined,
   "prettierExtensions": "md,json,yml,js,cjs,mjs,ts,cts,mts,java,html,css,scss",
@@ -1541,7 +1535,7 @@ exports[`generator - app with microservice should match snapshot 1`] = `
   "camelizedBaseName": "jhipster",
   "capitalizedBaseName": "Jhipster",
   "caret": undefined,
-  "cjsExtension": ".js",
+  "cjsExtension": ".cjs",
   "cli": undefined,
   "cliName": undefined,
   "clientBundler": undefined,
@@ -1913,7 +1907,7 @@ exports[`generator - app with microservice should match snapshot 1`] = `
   "messageBrokerPulsar": false,
   "microfrontend": false,
   "microfrontends": undefined,
-  "mjsExtension": ".mjs",
+  "mjsExtension": ".js",
   "monorepository": undefined,
   "nativeLanguage": "en",
   "nativeLanguageDefinition": {
@@ -1985,10 +1979,7 @@ exports[`generator - app with microservice should match snapshot 1`] = `
   ],
   "packageJsonNodeEngine": undefined,
   "packageJsonScripts": {},
-  "packageJsonType": "commonjs",
-  "packageJsonTypeAny": true,
-  "packageJsonTypeCommonjs": true,
-  "packageJsonTypeModule": false,
+  "packageJsonType": "module",
   "packageName": "com.mycompany.myapp",
   "pkType": undefined,
   "prettierExtensions": "md,json,yml,js,cjs,mjs,ts,cts,mts,java",
diff --git a/generators/base/blueprints.spec.ts b/generators/base/blueprints.spec.ts
index 07963ad8695d..fad2b13d3a25 100644
--- a/generators/base/blueprints.spec.ts
+++ b/generators/base/blueprints.spec.ts
@@ -294,7 +294,10 @@ describe('generator - base - local blueprint', () => {
     before(async () => {
       await helpers
         .runJHipster(BLUEPRINT_NS, { useEnvironmentBuilder: true })
-        .withFiles({ '.blueprint/app/index.mjs': BLUEPRINT_CONTENTS })
+        .withFiles({
+          '.blueprint/app/index.js': BLUEPRINT_CONTENTS,
+          '.blueprint/package.json': { type: 'module' },
+        })
         .commitFiles()
         .withJHipsterConfig();
     });
@@ -302,7 +305,10 @@ describe('generator - base - local blueprint', () => {
     it('creates expected default files', () => {
       expect(runResult.getStateSnapshot()).toMatchInlineSnapshot(`
 {
-  ".blueprint/app/index.mjs": {
+  ".blueprint/app/index.js": {
+    "stateCleared": "modified",
+  },
+  ".blueprint/package.json": {
     "stateCleared": "modified",
   },
   ".yo-rc.json": {
diff --git a/generators/ci-cd/__snapshots__/generator.spec.ts.snap b/generators/ci-cd/__snapshots__/generator.spec.ts.snap
index 3453290d6ac6..5cfd3be14c7c 100644
--- a/generators/ci-cd/__snapshots__/generator.spec.ts.snap
+++ b/generators/ci-cd/__snapshots__/generator.spec.ts.snap
@@ -64,7 +64,7 @@ exports[`generator - ci-cd cli with multiples values should match context snapsh
   "ciCdIntegrationsSonar": false,
   "ciCdJenkins": true,
   "ciCdTravis": false,
-  "cjsExtension": ".js",
+  "cjsExtension": ".cjs",
   "cli": undefined,
   "cliName": undefined,
   "clientBundler": "webpack",
@@ -230,7 +230,7 @@ exports[`generator - ci-cd cli with multiples values should match context snapsh
   "messageBrokerPulsar": false,
   "microfrontend": undefined,
   "microfrontends": undefined,
-  "mjsExtension": ".mjs",
+  "mjsExtension": ".js",
   "monorepository": undefined,
   "nativeLanguage": "en",
   "nativeLanguageDefinition": {
@@ -302,10 +302,7 @@ exports[`generator - ci-cd cli with multiples values should match context snapsh
   ],
   "packageJsonNodeEngine": undefined,
   "packageJsonScripts": {},
-  "packageJsonType": "commonjs",
-  "packageJsonTypeAny": true,
-  "packageJsonTypeCommonjs": true,
-  "packageJsonTypeModule": false,
+  "packageJsonType": "module",
   "packageName": "com.mycompany.myapp",
   "pkType": undefined,
   "prettierTabWidth": undefined,
diff --git a/generators/client/generators/bootstrap/__snapshots__/generator.spec.ts.snap b/generators/client/generators/bootstrap/__snapshots__/generator.spec.ts.snap
index 80a5f59dae65..b88c743744b1 100644
--- a/generators/client/generators/bootstrap/__snapshots__/generator.spec.ts.snap
+++ b/generators/client/generators/bootstrap/__snapshots__/generator.spec.ts.snap
@@ -40,7 +40,7 @@ exports[`generator - client:bootstrap bootstrapping default config should prepar
   "camelizedBaseName": "jhipster",
   "capitalizedBaseName": "Jhipster",
   "caret": undefined,
-  "cjsExtension": ".js",
+  "cjsExtension": ".cjs",
   "cli": undefined,
   "cliName": undefined,
   "clientBundler": "webpack",
@@ -181,7 +181,7 @@ exports[`generator - client:bootstrap bootstrapping default config should prepar
   "messageBrokerPulsar": false,
   "microfrontend": false,
   "microfrontends": undefined,
-  "mjsExtension": ".mjs",
+  "mjsExtension": ".js",
   "monorepository": undefined,
   "nativeLanguage": "en",
   "nativeLanguageDefinition": Any<Object>,
@@ -192,10 +192,7 @@ exports[`generator - client:bootstrap bootstrapping default config should prepar
   "packageFolder": undefined,
   "packageJsonNodeEngine": undefined,
   "packageJsonScripts": Any<Object>,
-  "packageJsonType": "commonjs",
-  "packageJsonTypeAny": true,
-  "packageJsonTypeCommonjs": true,
-  "packageJsonTypeModule": false,
+  "packageJsonType": "module",
   "packageName": "com.mycompany.myapp",
   "pkType": undefined,
   "prettierTabWidth": undefined,
diff --git a/generators/common/__snapshots__/generator.spec.ts.snap b/generators/common/__snapshots__/generator.spec.ts.snap
index 40c72fe29078..4ea9e9b3194d 100644
--- a/generators/common/__snapshots__/generator.spec.ts.snap
+++ b/generators/common/__snapshots__/generator.spec.ts.snap
@@ -153,6 +153,7 @@ This application was generated using JHipster JHIPSTER_VERSION, you can find doc
   "package.json": {
     "contents": "{
   "private": true,
+  "type": "module",
   "dependencies": {},
   "devDependencies": {
     "generator-jhipster": "JHIPSTER_VERSION",
diff --git a/generators/common/generators/bootstrap/__snapshots__/generator.spec.ts.snap b/generators/common/generators/bootstrap/__snapshots__/generator.spec.ts.snap
index 4e2c8580eb9a..cd68c0d95653 100644
--- a/generators/common/generators/bootstrap/__snapshots__/generator.spec.ts.snap
+++ b/generators/common/generators/bootstrap/__snapshots__/generator.spec.ts.snap
@@ -40,7 +40,7 @@ exports[`generator - common:bootstrap bootstrapping default config should prepar
   "camelizedBaseName": "jhipster",
   "capitalizedBaseName": "Jhipster",
   "caret": undefined,
-  "cjsExtension": ".js",
+  "cjsExtension": ".cjs",
   "cli": undefined,
   "cliName": undefined,
   "clientBundler": "webpack",
@@ -174,7 +174,7 @@ exports[`generator - common:bootstrap bootstrapping default config should prepar
   "messageBrokerPulsar": false,
   "microfrontend": false,
   "microfrontends": undefined,
-  "mjsExtension": ".mjs",
+  "mjsExtension": ".js",
   "monorepository": undefined,
   "nativeLanguage": "en",
   "nativeLanguageDefinition": Any<Object>,
@@ -185,10 +185,7 @@ exports[`generator - common:bootstrap bootstrapping default config should prepar
   "packageFolder": undefined,
   "packageJsonNodeEngine": undefined,
   "packageJsonScripts": Any<Object>,
-  "packageJsonType": "commonjs",
-  "packageJsonTypeAny": true,
-  "packageJsonTypeCommonjs": true,
-  "packageJsonTypeModule": false,
+  "packageJsonType": "module",
   "packageName": "com.mycompany.myapp",
   "pkType": undefined,
   "prettierTabWidth": undefined,
diff --git a/generators/generate-blueprint/__snapshots__/generator.spec.ts.snap b/generators/generate-blueprint/__snapshots__/generator.spec.ts.snap
index 3959fb0f8b8a..54cd6131ceec 100644
--- a/generators/generate-blueprint/__snapshots__/generator.spec.ts.snap
+++ b/generators/generate-blueprint/__snapshots__/generator.spec.ts.snap
@@ -2,16 +2,16 @@
 
 exports[`generator - generate-blueprint with all option should match snapshot 1`] = `
 {
-  ".blueprint/cli/commands.mjs": {
+  ".blueprint/cli/commands.js": {
     "stateCleared": "modified",
   },
-  ".blueprint/generate-sample/command.mjs": {
+  ".blueprint/generate-sample/command.js": {
     "stateCleared": "modified",
   },
-  ".blueprint/generate-sample/generator.mjs": {
+  ".blueprint/generate-sample/generator.js": {
     "stateCleared": "modified",
   },
-  ".blueprint/generate-sample/index.mjs": {
+  ".blueprint/generate-sample/index.js": {
     "stateCleared": "modified",
   },
   ".blueprint/generate-sample/templates/samples/sample.jdl": {
@@ -871,16 +871,16 @@ exports[`generator - generate-blueprint with all option should match snapshot 1`
 
 exports[`generator - generate-blueprint with default config should write files and match snapshot 1`] = `
 {
-  ".blueprint/cli/commands.mjs": {
+  ".blueprint/cli/commands.js": {
     "stateCleared": "modified",
   },
-  ".blueprint/generate-sample/command.mjs": {
+  ".blueprint/generate-sample/command.js": {
     "stateCleared": "modified",
   },
-  ".blueprint/generate-sample/generator.mjs": {
+  ".blueprint/generate-sample/generator.js": {
     "stateCleared": "modified",
   },
-  ".blueprint/generate-sample/index.mjs": {
+  ".blueprint/generate-sample/index.js": {
     "stateCleared": "modified",
   },
   ".blueprint/generate-sample/templates/samples/sample.jdl": {
diff --git a/generators/generate-blueprint/files.ts b/generators/generate-blueprint/files.ts
index 9c2bf7b87e22..290ebf5d6aaf 100644
--- a/generators/generate-blueprint/files.ts
+++ b/generators/generate-blueprint/files.ts
@@ -34,10 +34,10 @@ export const files = asWriteFilesSection<GenerateBlueprintApplication>({
         'tsconfig.json',
         'vitest.config.ts',
         'vitest.test-setup.ts',
-        '.blueprint/cli/commands.mjs',
-        '.blueprint/generate-sample/command.mjs',
-        '.blueprint/generate-sample/generator.mjs',
-        '.blueprint/generate-sample/index.mjs',
+        '.blueprint/cli/commands.js',
+        '.blueprint/generate-sample/command.js',
+        '.blueprint/generate-sample/generator.js',
+        '.blueprint/generate-sample/index.js',
         // Always write cli for devBlueprint usage
         'cli/cli.cjs',
         { sourceFile: 'cli/cli-customizations.cjs', override: false },
@@ -46,10 +46,10 @@ export const files = asWriteFilesSection<GenerateBlueprintApplication>({
     {
       condition: ctx => !ctx[LOCAL_BLUEPRINT_OPTION] && ctx.githubWorkflows,
       templates: [
-        '.blueprint/github-build-matrix/command.mjs',
-        '.blueprint/github-build-matrix/generator.mjs',
-        '.blueprint/github-build-matrix/generator.spec.mjs',
-        '.blueprint/github-build-matrix/index.mjs',
+        '.blueprint/github-build-matrix/command.js',
+        '.blueprint/github-build-matrix/generator.js',
+        '.blueprint/github-build-matrix/generator.spec.js',
+        '.blueprint/github-build-matrix/index.js',
       ],
     },
     {
@@ -73,21 +73,21 @@ export const generatorFiles = asWriteFilesSection<TemplateData>({
       path: 'generators/generator',
       to: ctx => `${ctx.application.blueprintsPath}${ctx.generator.replaceAll(':', '/generators/')}`,
       templates: [
-        { sourceFile: 'index.mjs', destinationFile: ctx => `index.${ctx.blueprintMjsExtension}` },
+        { sourceFile: 'index.js', destinationFile: _ctx => `index.js` },
         {
-          sourceFile: 'command.mjs',
-          destinationFile: ctx => `command.${ctx.blueprintMjsExtension}`,
+          sourceFile: 'command.js',
+          destinationFile: _ctx => `command.js`,
           override: data => !data.ignoreExistingGenerators,
         },
         {
-          sourceFile: 'generator.mjs.jhi',
-          destinationFile: ctx => `generator.${ctx.blueprintMjsExtension}.jhi`,
+          sourceFile: 'generator.js.jhi',
+          destinationFile: _ctx => `generator.js.jhi`,
           override: data => !data.ignoreExistingGenerators,
         },
         {
           condition: data => !data.generator.startsWith('entity') && !data.application[LOCAL_BLUEPRINT_OPTION],
-          sourceFile: 'generator.spec.mjs',
-          destinationFile: data => `generator.spec.${data.blueprintMjsExtension}`,
+          sourceFile: 'generator.spec.js',
+          destinationFile: _data => `generator.spec.js`,
           override: data => !data.ignoreExistingGenerators,
         },
       ],
diff --git a/generators/generate-blueprint/generator.spec.ts b/generators/generate-blueprint/generator.spec.ts
index ed4ca1da608e..67b100573ecc 100644
--- a/generators/generate-blueprint/generator.spec.ts
+++ b/generators/generate-blueprint/generator.spec.ts
@@ -95,13 +95,13 @@ describe(`generator - ${generator}`, () => {
       it('should write java files with gradle build tool and match snapshot', () => {
         expect(runResult.getStateSnapshot()).toMatchInlineSnapshot(`
 {
-  ".blueprint/app/command.mjs": {
+  ".blueprint/app/command.js": {
     "stateCleared": "modified",
   },
-  ".blueprint/app/generator.mjs": {
+  ".blueprint/app/generator.js": {
     "stateCleared": "modified",
   },
-  ".blueprint/app/index.mjs": {
+  ".blueprint/app/index.js": {
     "stateCleared": "modified",
   },
   ".blueprint/app/templates/template-file-app.ejs": {
diff --git a/generators/generate-blueprint/generator.ts b/generators/generate-blueprint/generator.ts
index f7b6b7528c6b..3ca6af116bf3 100644
--- a/generators/generate-blueprint/generator.ts
+++ b/generators/generate-blueprint/generator.ts
@@ -197,7 +197,7 @@ export default class extends BaseSimpleApplicationGenerator<
       prepare({ application }) {
         const { cli, cliName, baseName } = application;
         application.githubRepository = this.jhipsterConfig.githubRepository ?? `jhipster/generator-jhipster-${baseName}`;
-        application.blueprintMjsExtension = application.js ? 'js' : 'mjs';
+        application.blueprintMjsExtension = 'js';
         if (cli) {
           application.cliName = cliName ?? `jhipster-${baseName}`;
         }
@@ -215,7 +215,7 @@ export default class extends BaseSimpleApplicationGenerator<
         await control.cleanupFiles({
           '8.5.1': ['.eslintrc.json'],
           '8.7.2': ['.eslintignore', 'vitest.test-setup.ts'],
-          '8.7.4': ['.blueprint/generate-sample/get-samples.mjs', '.blueprint/github-build-matrix/build-matrix.mjs'],
+          '8.7.4': ['.blueprint/generate-sample/get-samples.js', '.blueprint/github-build-matrix/build-matrix.js'],
         });
       },
       async writing({ application }) {
@@ -318,6 +318,7 @@ export default class extends BaseSimpleApplicationGenerator<
         );
         this.packageJson.merge({
           name: `generator-jhipster-${application.baseName}`,
+          type: 'module',
           keywords: ['yeoman-generator', 'jhipster-blueprint', BLUEPRINT_API_VERSION],
           files: defaultPublishedFiles,
           scripts: {
diff --git a/generators/generate-blueprint/templates/.blueprint/cli/commands.mjs.ejs b/generators/generate-blueprint/templates/.blueprint/cli/commands.js.ejs
similarity index 100%
rename from generators/generate-blueprint/templates/.blueprint/cli/commands.mjs.ejs
rename to generators/generate-blueprint/templates/.blueprint/cli/commands.js.ejs
diff --git a/generators/generate-blueprint/templates/.blueprint/generate-sample/command.mjs.ejs b/generators/generate-blueprint/templates/.blueprint/generate-sample/command.js.ejs
similarity index 100%
rename from generators/generate-blueprint/templates/.blueprint/generate-sample/command.mjs.ejs
rename to generators/generate-blueprint/templates/.blueprint/generate-sample/command.js.ejs
diff --git a/generators/generate-blueprint/templates/.blueprint/generate-sample/generator.mjs.ejs b/generators/generate-blueprint/templates/.blueprint/generate-sample/generator.js.ejs
similarity index 100%
rename from generators/generate-blueprint/templates/.blueprint/generate-sample/generator.mjs.ejs
rename to generators/generate-blueprint/templates/.blueprint/generate-sample/generator.js.ejs
diff --git a/generators/generate-blueprint/templates/.blueprint/generate-sample/index.js.ejs b/generators/generate-blueprint/templates/.blueprint/generate-sample/index.js.ejs
new file mode 100644
index 000000000000..3eccd6e8659c
--- /dev/null
+++ b/generators/generate-blueprint/templates/.blueprint/generate-sample/index.js.ejs
@@ -0,0 +1,2 @@
+export { default } from './generator.js';
+export { default as command } from './command.js';
diff --git a/generators/generate-blueprint/templates/.blueprint/generate-sample/index.mjs.ejs b/generators/generate-blueprint/templates/.blueprint/generate-sample/index.mjs.ejs
deleted file mode 100644
index 3dd0513e5a14..000000000000
--- a/generators/generate-blueprint/templates/.blueprint/generate-sample/index.mjs.ejs
+++ /dev/null
@@ -1,2 +0,0 @@
-export { default } from './generator.mjs';
-export { default as command } from './command.mjs';
diff --git a/generators/generate-blueprint/templates/.blueprint/github-build-matrix/command.mjs.ejs b/generators/generate-blueprint/templates/.blueprint/github-build-matrix/command.js.ejs
similarity index 100%
rename from generators/generate-blueprint/templates/.blueprint/github-build-matrix/command.mjs.ejs
rename to generators/generate-blueprint/templates/.blueprint/github-build-matrix/command.js.ejs
diff --git a/generators/generate-blueprint/templates/.blueprint/github-build-matrix/generator.mjs.ejs b/generators/generate-blueprint/templates/.blueprint/github-build-matrix/generator.js.ejs
similarity index 100%
rename from generators/generate-blueprint/templates/.blueprint/github-build-matrix/generator.mjs.ejs
rename to generators/generate-blueprint/templates/.blueprint/github-build-matrix/generator.js.ejs
diff --git a/generators/generate-blueprint/templates/.blueprint/github-build-matrix/generator.spec.mjs.ejs b/generators/generate-blueprint/templates/.blueprint/github-build-matrix/generator.spec.js.ejs
similarity index 87%
rename from generators/generate-blueprint/templates/.blueprint/github-build-matrix/generator.spec.mjs.ejs
rename to generators/generate-blueprint/templates/.blueprint/github-build-matrix/generator.spec.js.ejs
index b3e4c15dc21f..1b9981d10922 100644
--- a/generators/generate-blueprint/templates/.blueprint/github-build-matrix/generator.spec.mjs.ejs
+++ b/generators/generate-blueprint/templates/.blueprint/github-build-matrix/generator.spec.js.ejs
@@ -13,7 +13,7 @@ describe(`generator - ${generator}`, async () => {
   for (const workflow of groups.map(sample => sample.split('.')[0])) {
     describe(`with ${workflow}`, () => {
       beforeAll(async () => {
-        await helpers.runJHipster(join(__dirname, 'index.mjs'), { useEnvironmentBuilder: true }).withArguments(workflow);
+        await helpers.runJHipster(join(__dirname, 'index.js'), { useEnvironmentBuilder: true }).withArguments(workflow);
       });
 
       it('should match matrix value', () => {
diff --git a/generators/generate-blueprint/templates/.blueprint/github-build-matrix/index.js.ejs b/generators/generate-blueprint/templates/.blueprint/github-build-matrix/index.js.ejs
new file mode 100644
index 000000000000..3eccd6e8659c
--- /dev/null
+++ b/generators/generate-blueprint/templates/.blueprint/github-build-matrix/index.js.ejs
@@ -0,0 +1,2 @@
+export { default } from './generator.js';
+export { default as command } from './command.js';
diff --git a/generators/generate-blueprint/templates/.blueprint/github-build-matrix/index.mjs.ejs b/generators/generate-blueprint/templates/.blueprint/github-build-matrix/index.mjs.ejs
deleted file mode 100644
index 3dd0513e5a14..000000000000
--- a/generators/generate-blueprint/templates/.blueprint/github-build-matrix/index.mjs.ejs
+++ /dev/null
@@ -1,2 +0,0 @@
-export { default } from './generator.mjs';
-export { default as command } from './command.mjs';
diff --git a/generators/generate-blueprint/templates/generators/generator/command.mjs.ejs b/generators/generate-blueprint/templates/generators/generator/command.js.ejs
similarity index 100%
rename from generators/generate-blueprint/templates/generators/generator/command.mjs.ejs
rename to generators/generate-blueprint/templates/generators/generator/command.js.ejs
diff --git a/generators/generate-blueprint/templates/generators/generator/generator.mjs.jhi.ejs b/generators/generate-blueprint/templates/generators/generator/generator.js.jhi.ejs
similarity index 98%
rename from generators/generate-blueprint/templates/generators/generator/generator.mjs.jhi.ejs
rename to generators/generate-blueprint/templates/generators/generator/generator.js.jhi.ejs
index 3129162a5e6b..16526304d3ad 100644
--- a/generators/generate-blueprint/templates/generators/generator/generator.mjs.jhi.ejs
+++ b/generators/generate-blueprint/templates/generators/generator/generator.js.jhi.ejs
@@ -28,7 +28,7 @@
 import <%= generatorClass %>Generator from 'generator-jhipster/generators/<%= jhipsterGenerator %>';
 <%_ } _%>
 <%_ if (priorities.find(priority => priority.name === 'initializing')) { _%>
-import command from './command.<%- blueprintMjsExtension %>';
+import command from './command.js';
 <%_ } _%>
 
 <%_ if (application.dynamic) { _%>
diff --git a/generators/generate-blueprint/templates/generators/generator/generator.spec.mjs.ejs b/generators/generate-blueprint/templates/generators/generator/generator.spec.js.ejs
similarity index 100%
rename from generators/generate-blueprint/templates/generators/generator/generator.spec.mjs.ejs
rename to generators/generate-blueprint/templates/generators/generator/generator.spec.js.ejs
diff --git a/generators/generate-blueprint/templates/generators/generator/index.mjs.ejs b/generators/generate-blueprint/templates/generators/generator/index.js.ejs
similarity index 85%
rename from generators/generate-blueprint/templates/generators/generator/index.mjs.ejs
rename to generators/generate-blueprint/templates/generators/generator/index.js.ejs
index 139141f0252d..bb3c8d3f3567 100644
--- a/generators/generate-blueprint/templates/generators/generator/index.mjs.ejs
+++ b/generators/generate-blueprint/templates/generators/generator/index.js.ejs
@@ -16,5 +16,5 @@
  See the License for the specific language governing permissions and
  limitations under the License.
 -%>
-export { <%- application.dynamic ? 'createGenerator' : 'default' %> } from './generator.<%- blueprintMjsExtension %>';
-export { default as command } from './command.<%- blueprintMjsExtension %>';
+export { <%- application.dynamic ? 'createGenerator' : 'default' %> } from './generator.js';
+export { default as command } from './command.js';
diff --git a/generators/java/generators/bootstrap/__snapshots__/generator.spec.ts.snap b/generators/java/generators/bootstrap/__snapshots__/generator.spec.ts.snap
index f98fce4427b4..a9bbce7cf9aa 100644
--- a/generators/java/generators/bootstrap/__snapshots__/generator.spec.ts.snap
+++ b/generators/java/generators/bootstrap/__snapshots__/generator.spec.ts.snap
@@ -40,7 +40,7 @@ exports[`generator - java:bootstrap bootstrapping default config should prepare
   "camelizedBaseName": "jhipster",
   "capitalizedBaseName": "Jhipster",
   "caret": undefined,
-  "cjsExtension": ".js",
+  "cjsExtension": ".cjs",
   "cli": undefined,
   "cliName": undefined,
   "clientBundler": "webpack",
@@ -193,7 +193,7 @@ exports[`generator - java:bootstrap bootstrapping default config should prepare
   "messageBrokerPulsar": false,
   "microfrontend": false,
   "microfrontends": undefined,
-  "mjsExtension": ".mjs",
+  "mjsExtension": ".js",
   "monorepository": undefined,
   "nativeLanguage": "en",
   "nativeLanguageDefinition": Any<Object>,
@@ -208,10 +208,7 @@ exports[`generator - java:bootstrap bootstrapping default config should prepare
   "packageInfoJavadocs": Any<Array>,
   "packageJsonNodeEngine": undefined,
   "packageJsonScripts": Any<Object>,
-  "packageJsonType": "commonjs",
-  "packageJsonTypeAny": true,
-  "packageJsonTypeCommonjs": true,
-  "packageJsonTypeModule": false,
+  "packageJsonType": "module",
   "packageName": "com.mycompany.myapp",
   "pkType": undefined,
   "prettierTabWidth": undefined,
diff --git a/generators/javascript/__snapshots__/generator.spec.ts.snap b/generators/javascript/__snapshots__/generator.spec.ts.snap
index 8b1675503e9c..91d680111ba1 100644
--- a/generators/javascript/__snapshots__/generator.spec.ts.snap
+++ b/generators/javascript/__snapshots__/generator.spec.ts.snap
@@ -10,6 +10,7 @@ exports[`generator - javascript with defaults options should match files snapsho
   "package.json": {
     "contents": "{
   "private": true,
+  "type": "module",
   "dependencies": {},
   "devDependencies": {},
   "engines": {},
diff --git a/generators/javascript/generator.spec.ts b/generators/javascript/generator.spec.ts
index 99b42ec17440..6bccefafb712 100644
--- a/generators/javascript/generator.spec.ts
+++ b/generators/javascript/generator.spec.ts
@@ -55,5 +55,15 @@ describe(`generator - ${generator}`, () => {
     it('should compose with generators', () => {
       expect(result.getComposedGenerators()).toMatchInlineSnapshot(`[]`);
     });
+
+    it('should use ESM by default in package.json', () => {
+      result.assertFileContent('package.json', /"type": "module"/);
+    });
+
+    it('should not create any .mjs files', () => {
+      const files = result.getSnapshot();
+      const mjsFiles = Object.keys(files).filter(filename => filename.endsWith('.mjs'));
+      expect(mjsFiles).toHaveLength(0);
+    });
   });
 });
diff --git a/generators/javascript/generator.ts b/generators/javascript/generator.ts
index 75c3f2daa3c0..967ad976befb 100644
--- a/generators/javascript/generator.ts
+++ b/generators/javascript/generator.ts
@@ -66,14 +66,7 @@ export default class JavascriptGenerator extends JavascriptSimpleApplicationGene
   get postWriting() {
     return this.asPostWritingTaskGroup({
       mergePackageJson({ application, source }) {
-        const {
-          packageJsonNodeEngine,
-          packageJsonType,
-          dasherizedBaseName,
-          projectDescription,
-          packageJsonScripts,
-          clientPackageJsonScripts,
-        } = application;
+        const { packageJsonNodeEngine, dasherizedBaseName, projectDescription, packageJsonScripts, clientPackageJsonScripts } = application;
 
         this.packageJson.merge({ scripts: packageJsonScripts! });
 
@@ -84,9 +77,7 @@ export default class JavascriptGenerator extends JavascriptSimpleApplicationGene
           license: 'UNLICENSED',
         });
 
-        if (packageJsonType === 'module') {
-          this.packageJson.merge({ type: packageJsonType });
-        }
+        this.packageJson.merge({ type: 'module' });
 
         if (packageJsonNodeEngine) {
           const packageJsonEngines: any = this.packageJson.get('engines') ?? {};
diff --git a/generators/javascript/generators/bootstrap/__snapshots__/generator.spec.ts.snap b/generators/javascript/generators/bootstrap/__snapshots__/generator.spec.ts.snap
index 4a2e8f855ecc..2525168aa314 100644
--- a/generators/javascript/generators/bootstrap/__snapshots__/generator.spec.ts.snap
+++ b/generators/javascript/generators/bootstrap/__snapshots__/generator.spec.ts.snap
@@ -34,7 +34,7 @@ exports[`generator - javascript:bootstrap bootstrapping default config should pr
   "camelizedBaseName": "jhipster",
   "capitalizedBaseName": "Jhipster",
   "caret": undefined,
-  "cjsExtension": ".js",
+  "cjsExtension": ".cjs",
   "cli": undefined,
   "cliName": undefined,
   "clientBundler": "webpack",
@@ -154,7 +154,7 @@ exports[`generator - javascript:bootstrap bootstrapping default config should pr
   "messageBrokerPulsar": false,
   "microfrontend": false,
   "microfrontends": undefined,
-  "mjsExtension": ".mjs",
+  "mjsExtension": ".js",
   "monorepository": undefined,
   "nativeLanguage": "en",
   "nodeDependencies": Any<Object>,
@@ -163,10 +163,7 @@ exports[`generator - javascript:bootstrap bootstrapping default config should pr
   "nodeVersion": "NODE_VERSION",
   "packageFolder": undefined,
   "packageJsonNodeEngine": undefined,
-  "packageJsonType": "commonjs",
-  "packageJsonTypeAny": true,
-  "packageJsonTypeCommonjs": true,
-  "packageJsonTypeModule": false,
+  "packageJsonType": "module",
   "packageName": "com.mycompany.myapp",
   "pkType": undefined,
   "prettierTabWidth": undefined,
@@ -693,9 +690,9 @@ exports[`generator - javascript:bootstrap bootstrapping default config should pr
 ]
 `;
 
-exports[`generator - javascript:bootstrap customVersion-commonjs should call source snapshot 1`] = `{}`;
+exports[`generator - javascript:bootstrap customVersion-module should call source snapshot 1`] = `{}`;
 
-exports[`generator - javascript:bootstrap customVersion-commonjs should match files snapshot 1`] = `
+exports[`generator - javascript:bootstrap customVersion-module should match files snapshot 1`] = `
 {
   ".yo-rc.json": ObjectContaining {
     "contents": Any<String>,
@@ -713,9 +710,9 @@ exports[`generator - javascript:bootstrap packageJsonNodeEngine(false)-module sh
 }
 `;
 
-exports[`generator - javascript:bootstrap packageJsonNodeEngine(true) should call source snapshot 1`] = `{}`;
+exports[`generator - javascript:bootstrap packageJsonNodeEngine(true)-module should call source snapshot 1`] = `{}`;
 
-exports[`generator - javascript:bootstrap packageJsonNodeEngine(true) should match files snapshot 1`] = `
+exports[`generator - javascript:bootstrap packageJsonNodeEngine(true)-module should match files snapshot 1`] = `
 {
   ".yo-rc.json": ObjectContaining {
     "contents": Any<String>,
diff --git a/generators/javascript/generators/bootstrap/command.ts b/generators/javascript/generators/bootstrap/command.ts
index b2465b3263e9..1d6e7b83e41a 100644
--- a/generators/javascript/generators/bootstrap/command.ts
+++ b/generators/javascript/generators/bootstrap/command.ts
@@ -33,8 +33,7 @@ const command = {
         type: String,
         hide: true,
       },
-      choices: ['commonjs', 'module'],
-      default: 'commonjs',
+      default: 'module',
       scope: 'storage',
     },
   },
diff --git a/generators/javascript/generators/bootstrap/generator.spec.ts b/generators/javascript/generators/bootstrap/generator.spec.ts
index 8a0f28429239..b9ed812abc7e 100644
--- a/generators/javascript/generators/bootstrap/generator.spec.ts
+++ b/generators/javascript/generators/bootstrap/generator.spec.ts
@@ -37,7 +37,7 @@ describe(`generator - ${generator}`, () => {
 
   for (const [name, config] of Object.entries(
     extendMatrix(fromMatrix({ packageJsonNodeEngine: [true, false, 'customVersion'] }), {
-      packageJsonType: [undefined, 'commonjs', 'module'],
+      packageJsonType: ['module'],
     }),
   )) {
     describe(name, () => {
diff --git a/generators/javascript/generators/bootstrap/generator.ts b/generators/javascript/generators/bootstrap/generator.ts
index 28df4aa32ce7..390f9139ba13 100644
--- a/generators/javascript/generators/bootstrap/generator.ts
+++ b/generators/javascript/generators/bootstrap/generator.ts
@@ -38,11 +38,10 @@ export default class JavascriptBootstrapGenerator extends JavascriptSimpleApplic
           this.fetchFromInstalledJHipster('javascript', 'resources', 'package.json'),
         );
       },
-      jsExtensions({ applicationDefaults, application }) {
+      jsExtensions({ applicationDefaults, application: _application }) {
         applicationDefaults({
-          cjsExtension: application.packageJsonTypeCommonjs ? '.js' : '.cjs',
-          mjsExtension: application.packageJsonTypeModule ? '.js' : '.mjs',
-
+          cjsExtension: '.cjs',
+          mjsExtension: '.js',
           clientRootDir: '',
           clientSrcDir: ({ clientRootDir }) => `${clientRootDir}${clientRootDir ? 'src/' : CLIENT_MAIN_SRC_DIR}`,
         });
diff --git a/generators/javascript/generators/eslint/__snapshots__/generator.spec.ts.snap b/generators/javascript/generators/eslint/__snapshots__/generator.spec.ts.snap
index 5a6190d766a3..b5dd564105f0 100644
--- a/generators/javascript/generators/eslint/__snapshots__/generator.spec.ts.snap
+++ b/generators/javascript/generators/eslint/__snapshots__/generator.spec.ts.snap
@@ -7,7 +7,7 @@ exports[`generator - javascript:eslint with defaults options should match files
   ".yo-rc.json": ObjectContaining {
     "contents": Any<String>,
   },
-  "eslint.config.mjs": {
+  "eslint.config.js": {
     "contents": "import globals from 'globals';
 import prettier from 'eslint-plugin-prettier/recommended';
 // jhipster-needle-eslint-add-import - JHipster will add additional import here
diff --git a/generators/javascript/generators/eslint/generator.ts b/generators/javascript/generators/eslint/generator.ts
index 419ec844ca85..a070f5c55f7a 100644
--- a/generators/javascript/generators/eslint/generator.ts
+++ b/generators/javascript/generators/eslint/generator.ts
@@ -48,7 +48,7 @@ export default class EslintGenerator extends JavascriptSimpleApplicationGenerato
   get preparing() {
     return this.asPreparingTaskGroup({
       source({ application, source }) {
-        application.eslintConfigFile = `eslint.config.${application.packageJsonType === 'module' ? 'js' : 'mjs'}`;
+        application.eslintConfigFile = `eslint.config.js`;
         source.addEslintConfig = ({ import: importToAdd, config }) =>
           this.editFile(
             application.eslintConfigFile!,
diff --git a/generators/javascript/templates/package.json.ejs b/generators/javascript/templates/package.json.ejs
index e222632892f0..a2a03d793ab8 100644
--- a/generators/javascript/templates/package.json.ejs
+++ b/generators/javascript/templates/package.json.ejs
@@ -18,6 +18,7 @@
 -%>
 {
   "private": true,
+  "type": "module",
   "dependencies": {},
   "devDependencies": {},
   "engines": {},
diff --git a/generators/react/__snapshots__/generator.spec.ts.snap b/generators/react/__snapshots__/generator.spec.ts.snap
index befe2b726d61..3e62e79060f8 100644
--- a/generators/react/__snapshots__/generator.spec.ts.snap
+++ b/generators/react/__snapshots__/generator.spec.ts.snap
@@ -17,7 +17,7 @@ exports[`generator - react gateway-jwt-skipUserManagement(true)-withAdminUi(fals
   ".yo-rc.json": {
     "stateCleared": "modified",
   },
-  "clientRoot/eslint.config.mjs": {
+  "clientRoot/eslint.config.js": {
     "stateCleared": "modified",
   },
   "clientRoot/jest.conf.js": {
@@ -480,7 +480,7 @@ exports[`generator - react gateway-oauth2-withAdminUi(true)-skipJhipsterDependen
   ".yo-rc.json": {
     "stateCleared": "modified",
   },
-  "clientRoot/eslint.config.mjs": {
+  "clientRoot/eslint.config.js": {
     "stateCleared": "modified",
   },
   "clientRoot/jest.conf.js": {
@@ -976,7 +976,7 @@ exports[`generator - react microservice-jwt-skipUserManagement(false)-withAdminU
   ".yo-rc.json": {
     "stateCleared": "modified",
   },
-  "clientRoot/eslint.config.mjs": {
+  "clientRoot/eslint.config.js": {
     "stateCleared": "modified",
   },
   "clientRoot/jest.conf.js": {
@@ -1455,7 +1455,7 @@ exports[`generator - react microservice-oauth2-withAdminUi(true)-skipJhipsterDep
   ".yo-rc.json": {
     "stateCleared": "modified",
   },
-  "eslint.config.mjs": {
+  "eslint.config.js": {
     "stateCleared": "modified",
   },
   "jest.conf.js": {
@@ -1949,7 +1949,7 @@ exports[`generator - react monolith-jwt-skipUserManagement(false)-withAdminUi(tr
   ".yo-rc.json": {
     "stateCleared": "modified",
   },
-  "eslint.config.mjs": {
+  "eslint.config.js": {
     "stateCleared": "modified",
   },
   "jest.conf.js": {
@@ -2502,7 +2502,7 @@ exports[`generator - react monolith-oauth2-withAdminUi(false)-skipJhipsterDepend
   ".yo-rc.json": {
     "stateCleared": "modified",
   },
-  "eslint.config.mjs": {
+  "eslint.config.js": {
     "stateCleared": "modified",
   },
   "jest.conf.js": {
@@ -2965,7 +2965,7 @@ exports[`generator - react monolith-session-skipUserManagement(true)-withAdminUi
   ".yo-rc.json": {
     "stateCleared": "modified",
   },
-  "eslint.config.mjs": {
+  "eslint.config.js": {
     "stateCleared": "modified",
   },
   "jest.conf.js": {
diff --git a/generators/react/generator.spec.ts b/generators/react/generator.spec.ts
index b6ee6e74df53..f335d6f77bab 100644
--- a/generators/react/generator.spec.ts
+++ b/generators/react/generator.spec.ts
@@ -78,6 +78,16 @@ describe(`generator - ${clientFramework}`, () => {
         runResult.assertNoFileContent(`${clientRootDir}package.json`, /VERSION_MANAGED_BY_CLIENT_VUE/);
       });
 
+      it('should use ESM by default in package.json', () => {
+        runResult.assertFileContent(`${clientRootDir}package.json`, /"type": "module"/);
+      });
+
+      it('should not create files with .mjs extension', () => {
+        const generatedFiles = runResult.getStateSnapshot();
+        const mjsFiles = Object.keys(generatedFiles).filter(file => file.endsWith('.mjs'));
+        expect(mjsFiles).toHaveLength(0);
+      });
+
       describe('withAdminUi', () => {
         const { applicationType, withAdminUi } = sampleConfig;
         const clientSrcDir = `${clientRootDir}${clientRootDir ? 'src/' : CLIENT_MAIN_SRC_DIR}`;
diff --git a/generators/react/generator.ts b/generators/react/generator.ts
index 2036c5fe2f75..e3a2d80647dc 100644
--- a/generators/react/generator.ts
+++ b/generators/react/generator.ts
@@ -96,7 +96,7 @@ export default class ReactGenerator extends ClientApplicationGenerator<
 
         applicationDefaults({
           __override__: true,
-          eslintConfigFile: app => `eslint.config.${app.packageJsonType === 'module' ? 'js' : 'mjs'}`,
+          eslintConfigFile: _app => `eslint.config.js`,
           webappEnumerationsDir: app => `${app.clientSrcDir}app/shared/model/enumerations/`,
         });
       },
diff --git a/generators/react/templates/package.json.ejs b/generators/react/templates/package.json.ejs
index 6ab4df52aac0..1ac0f55ee365 100644
--- a/generators/react/templates/package.json.ejs
+++ b/generators/react/templates/package.json.ejs
@@ -21,6 +21,7 @@
   "version": "0.0.1-SNAPSHOT",
   "description": "<%= projectDescription %>",
   "private": true,
+  "type": "module",
   "license": "UNLICENSED",
   "cacheDirectories": [
     "node_modules"
diff --git a/generators/server/generators/bootstrap/__snapshots__/generator.spec.ts.snap b/generators/server/generators/bootstrap/__snapshots__/generator.spec.ts.snap
index 2e71ebebc923..f8b3b6ebf123 100644
--- a/generators/server/generators/bootstrap/__snapshots__/generator.spec.ts.snap
+++ b/generators/server/generators/bootstrap/__snapshots__/generator.spec.ts.snap
@@ -40,7 +40,7 @@ exports[`generator - server:bootstrap bootstrapping default config should prepar
   "camelizedBaseName": "jhipster",
   "capitalizedBaseName": "Jhipster",
   "caret": undefined,
-  "cjsExtension": ".js",
+  "cjsExtension": ".cjs",
   "cli": undefined,
   "cliName": undefined,
   "clientBundler": "webpack",
@@ -184,7 +184,7 @@ exports[`generator - server:bootstrap bootstrapping default config should prepar
   "messageBrokerPulsar": false,
   "microfrontend": false,
   "microfrontends": undefined,
-  "mjsExtension": ".mjs",
+  "mjsExtension": ".js",
   "monorepository": undefined,
   "nativeLanguage": "en",
   "nativeLanguageDefinition": Any<Object>,
@@ -196,10 +196,7 @@ exports[`generator - server:bootstrap bootstrapping default config should prepar
   "packageInfoJavadocs": Any<Array>,
   "packageJsonNodeEngine": undefined,
   "packageJsonScripts": Any<Object>,
-  "packageJsonType": "commonjs",
-  "packageJsonTypeAny": true,
-  "packageJsonTypeCommonjs": true,
-  "packageJsonTypeModule": false,
+  "packageJsonType": "module",
   "packageName": "com.mycompany.myapp",
   "pkType": undefined,
   "prettierTabWidth": undefined,
diff --git a/generators/spring-boot/generators/bootstrap/__snapshots__/generator.spec.ts.snap b/generators/spring-boot/generators/bootstrap/__snapshots__/generator.spec.ts.snap
index 94f07f31774a..8dfd81f253d3 100644
--- a/generators/spring-boot/generators/bootstrap/__snapshots__/generator.spec.ts.snap
+++ b/generators/spring-boot/generators/bootstrap/__snapshots__/generator.spec.ts.snap
@@ -40,7 +40,7 @@ exports[`generator - spring-boot:bootstrap bootstrapping default config should p
   "camelizedBaseName": "jhipster",
   "capitalizedBaseName": "Jhipster",
   "caret": undefined,
-  "cjsExtension": ".js",
+  "cjsExtension": ".cjs",
   "cli": undefined,
   "cliName": undefined,
   "clientBundler": "webpack",
@@ -193,7 +193,7 @@ exports[`generator - spring-boot:bootstrap bootstrapping default config should p
   "messageBrokerPulsar": false,
   "microfrontend": false,
   "microfrontends": undefined,
-  "mjsExtension": ".mjs",
+  "mjsExtension": ".js",
   "monorepository": undefined,
   "nativeLanguage": "en",
   "nativeLanguageDefinition": Any<Object>,
@@ -208,10 +208,7 @@ exports[`generator - spring-boot:bootstrap bootstrapping default config should p
   "packageInfoJavadocs": Any<Array>,
   "packageJsonNodeEngine": undefined,
   "packageJsonScripts": Any<Object>,
-  "packageJsonType": "commonjs",
-  "packageJsonTypeAny": true,
-  "packageJsonTypeCommonjs": true,
-  "packageJsonTypeModule": false,
+  "packageJsonType": "module",
   "packageName": "com.mycompany.myapp",
   "pkType": undefined,
   "prettierTabWidth": undefined,
diff --git a/generators/spring-boot/templates/package.json.ejs b/generators/spring-boot/templates/package.json.ejs
index 608aaf94a519..e0798b192e32 100644
--- a/generators/spring-boot/templates/package.json.ejs
+++ b/generators/spring-boot/templates/package.json.ejs
@@ -21,6 +21,7 @@
   "version": "0.0.0",
   "description": "Description for <%= baseName %>",
   "private": true,
+  "type": "module",
   "license": "UNLICENSED",
   "cacheDirectories": [
     "node_modules"
diff --git a/generators/vue/__snapshots__/generator.spec.ts.snap b/generators/vue/__snapshots__/generator.spec.ts.snap
index 7839f05e7b03..db6684eec223 100644
--- a/generators/vue/__snapshots__/generator.spec.ts.snap
+++ b/generators/vue/__snapshots__/generator.spec.ts.snap
@@ -20,7 +20,7 @@ exports[`generator - vue gateway-jwt-skipUserManagement(true)-withAdminUi(false)
   "clientRoot/.postcssrc.js": {
     "stateCleared": "modified",
   },
-  "clientRoot/eslint.config.mjs": {
+  "clientRoot/eslint.config.js": {
     "stateCleared": "modified",
   },
   "clientRoot/package.json": {
@@ -531,7 +531,7 @@ exports[`generator - vue gateway-oauth2-withAdminUi(true)-skipJhipsterDependenci
   "clientRoot/.postcssrc.js": {
     "stateCleared": "modified",
   },
-  "clientRoot/eslint.config.mjs": {
+  "clientRoot/eslint.config.js": {
     "stateCleared": "modified",
   },
   "clientRoot/package.json": {
@@ -1114,7 +1114,7 @@ exports[`generator - vue microservice-jwt-skipUserManagement(false)-withAdminUi(
   "clientRoot/.postcssrc.js": {
     "stateCleared": "modified",
   },
-  "clientRoot/eslint.config.mjs": {
+  "clientRoot/eslint.config.js": {
     "stateCleared": "modified",
   },
   "clientRoot/module-federation.config.cjs": {
@@ -1660,7 +1660,7 @@ exports[`generator - vue microservice-oauth2-withAdminUi(true)-skipJhipsterDepen
   ".yo-rc.json": {
     "stateCleared": "modified",
   },
-  "eslint.config.mjs": {
+  "eslint.config.js": {
     "stateCleared": "modified",
   },
   "module-federation.config.cjs": {
@@ -2205,7 +2205,7 @@ exports[`generator - vue monolith-jwt-skipUserManagement(false)-withAdminUi(true
   ".yo-rc.json": {
     "stateCleared": "modified",
   },
-  "eslint.config.mjs": {
+  "eslint.config.js": {
     "stateCleared": "modified",
   },
   "package.json": {
@@ -2872,7 +2872,7 @@ exports[`generator - vue monolith-oauth2-withAdminUi(false)-skipJhipsterDependen
   ".yo-rc.json": {
     "stateCleared": "modified",
   },
-  "eslint.config.mjs": {
+  "eslint.config.js": {
     "stateCleared": "modified",
   },
   "package.json": {
@@ -3359,7 +3359,7 @@ exports[`generator - vue monolith-session-skipUserManagement(true)-withAdminUi(f
   ".yo-rc.json": {
     "stateCleared": "modified",
   },
-  "eslint.config.mjs": {
+  "eslint.config.js": {
     "stateCleared": "modified",
   },
   "package.json": {
diff --git a/generators/vue/generator.spec.ts b/generators/vue/generator.spec.ts
index 0063ed790148..88a9a1408802 100644
--- a/generators/vue/generator.spec.ts
+++ b/generators/vue/generator.spec.ts
@@ -93,6 +93,16 @@ describe(`generator - ${clientFramework}`, () => {
         runResult.assertNoFileContent(`${clientRootDir}package.json`, /VERSION_MANAGED_BY_CLIENT_VUE/);
       });
 
+      it('should use ESM by default in package.json', () => {
+        runResult.assertFileContent(`${clientRootDir}package.json`, /"type": "module"/);
+      });
+
+      it('should not create files with .mjs extension', () => {
+        const generatedFiles = runResult.getStateSnapshot();
+        const mjsFiles = Object.keys(generatedFiles).filter(file => file.endsWith('.mjs'));
+        expect(mjsFiles).toHaveLength(0);
+      });
+
       describe('withAdminUi', () => {
         const { applicationType, withAdminUi } = sampleConfig;
         const clientSrcDir = `${clientRootDir}${clientRootDir ? 'src/' : CLIENT_MAIN_SRC_DIR}`;
diff --git a/generators/vue/generator.ts b/generators/vue/generator.ts
index 706b6963d091..6cd9000d6898 100644
--- a/generators/vue/generator.ts
+++ b/generators/vue/generator.ts
@@ -98,7 +98,7 @@ export default class VueGenerator extends ClientApplicationGenerator {
       applicationDefauts({ applicationDefaults }) {
         applicationDefaults({
           __override__: true,
-          eslintConfigFile: app => `eslint.config.${app.packageJsonType === 'module' ? 'js' : 'mjs'}`,
+          eslintConfigFile: _app => `eslint.config.js`,
           clientWebappDir: app => `${app.clientSrcDir}app/`,
           webappEnumerationsDir: app => `${app.clientWebappDir}shared/model/enumerations/`,
         });
diff --git a/generators/vue/templates/package.json.ejs b/generators/vue/templates/package.json.ejs
index 0376de1e58dc..38d44642a406 100644
--- a/generators/vue/templates/package.json.ejs
+++ b/generators/vue/templates/package.json.ejs
@@ -21,6 +21,7 @@
   "version": "0.0.0",
   "description": "<%= projectDescription %>",
   "private": true,
+  "type": "module",
   "license": "UNLICENSED",
   "cacheDirectories": [
     "node_modules"
diff --git a/generators/vue/templates/vitest.config.mts.ejs b/generators/vue/templates/vitest.config.mts.ejs
index 141ffb3aa73f..e9110c89959f 100644
--- a/generators/vue/templates/vitest.config.mts.ejs
+++ b/generators/vue/templates/vitest.config.mts.ejs
@@ -18,7 +18,7 @@
 -%>
 import { fileURLToPath } from 'node:url'
 import { mergeConfig, defineConfig } from 'vitest/config';
-import viteConfig from './vite.config.mjs'
+import viteConfig from './vite.config.js'
 
 export default mergeConfig(
   viteConfig,