diff --git a/ern-api-gen/src/generateProject.ts b/ern-api-gen/src/generateProject.ts
index c3e576a60..a306e063b 100644
--- a/ern-api-gen/src/generateProject.ts
+++ b/ern-api-gen/src/generateProject.ts
@@ -82,7 +82,7 @@ export function generatePackageJson({
       name: npmScope ? `@${npmScope}/${packageName}` : packageName,
       version: apiVersion ?? '1.0.0',
       description: apiDescription,
-      main: 'javascript/src/index.js',
+      main: 'javascript/src/index.d.ts',
       scripts: {
         flow: 'flow',
       },
diff --git a/ern-api-gen/src/languages/ErnES6ApiCodegen.ts b/ern-api-gen/src/languages/ErnES6ApiCodegen.ts
index 2db3a6315..047dde41c 100644
--- a/ern-api-gen/src/languages/ErnES6ApiCodegen.ts
+++ b/ern-api-gen/src/languages/ErnES6ApiCodegen.ts
@@ -32,14 +32,14 @@ export default class ErnES6ApiCodegen extends ES6Codegen {
     this.__apiTestTemplateFiles.clear();
     this.__apiDocTemplateFiles.clear();
     // add our special sauce.
-    this.__apiTemplateFiles.put('api.mustache', '.js');
-    this.__apiTemplateFiles.put('apirequests.mustache', '.js');
-    this.__apiTemplateFiles.put('apievents.mustache', '.js');
-    this.__apiTestTemplateFiles.put('api_test.mustache', '.js');
+    this.__apiTemplateFiles.put('api.mustache', '.ts');
+    this.__apiTemplateFiles.put('apirequests.mustache', '.ts');
+    this.__apiTemplateFiles.put('apievents.mustache', '.ts');
+    this.__apiTestTemplateFiles.put('api_test.mustache', '.ts');
     // this.__apiDocTemplateFiles.put("api_doc.mustache", ".md");
     if (this.classy) {
       this.__additionalProperties.put('isClassy', this.classy);
-      this.__modelTemplateFiles.put('model.mustache', '.js');
+      this.__modelTemplateFiles.put('model.mustache', '.ts');
       // this.__modelDocTemplateFiles.put("model_doc.mustache", ".md");
     }
   }
diff --git a/ern-api-gen/src/languages/JavascriptClientCodegen.ts b/ern-api-gen/src/languages/JavascriptClientCodegen.ts
index dfa675dfd..2e716fc45 100644
--- a/ern-api-gen/src/languages/JavascriptClientCodegen.ts
+++ b/ern-api-gen/src/languages/JavascriptClientCodegen.ts
@@ -132,10 +132,10 @@ export default class JavascriptClientCodegen extends DefaultCodegen {
 
   constructor() {
     super();
-    this.__modelTemplateFiles.put('model.mustache', '.js');
-    this.__modelTestTemplateFiles.put('model_test.mustache', '.js');
-    this.__apiTemplateFiles.put('api.mustache', '.js');
-    this.__apiTestTemplateFiles.put('api_test.mustache', '.js');
+    this.__modelTemplateFiles.put('model.mustache', '.ts');
+    this.__modelTestTemplateFiles.put('model_test.mustache', '.ts');
+    this.__apiTemplateFiles.put('api.mustache', '.ts');
+    this.__apiTestTemplateFiles.put('api_test.mustache', '.ts');
     this.__modelDocTemplateFiles.put('model_doc.mustache', '.md');
     this.__apiDocTemplateFiles.put('api_doc.mustache', '.md');
     this.__defaultIncludes = newHashSet(...this.__languageSpecificPrimitives);
@@ -566,14 +566,14 @@ export default class JavascriptClientCodegen extends DefaultCodegen {
       new SupportingFile(
         'index.mustache',
         this.createPath(this.sourceFolder, this.invokerPackage),
-        'index.js',
+        'index.d.ts',
       ),
     );
     this.__supportingFiles.push(
       new SupportingFile(
         'ApiClient.mustache',
         this.createPath(this.sourceFolder, this.invokerPackage),
-        'ApiClient.js',
+        'ApiClient.ts',
       ),
     );
   }
diff --git a/ern-api-gen/test/generateProject-test.js b/ern-api-gen/test/generateProject-test.js
index 87539528e..155b8e339 100644
--- a/ern-api-gen/test/generateProject-test.js
+++ b/ern-api-gen/test/generateProject-test.js
@@ -39,7 +39,7 @@ describe('generatePackageJson', function () {
     expect(result).to.deep.equal({
       name: 'test',
       version: '1.0.0',
-      main: 'javascript/src/index.js',
+      main: 'javascript/src/index.d.ts',
       scripts: {
         flow: 'flow',
       },
@@ -70,7 +70,7 @@ describe('generatePackageJson', function () {
       name: 'test',
       version: '1.0.0',
       license: 'ISC',
-      main: 'javascript/src/index.js',
+      main: 'javascript/src/index.d.ts',
       scripts: {
         flow: 'flow',
       },