diff --git a/modules/openapi-generator/src/main/resources/Javascript-Apollo/api.mustache b/modules/openapi-generator/src/main/resources/Javascript-Apollo/api.mustache
index 87b27a51ad9..63cb101aadb 100644
--- a/modules/openapi-generator/src/main/resources/Javascript-Apollo/api.mustache
+++ b/modules/openapi-generator/src/main/resources/Javascript-Apollo/api.mustache
@@ -53,7 +53,8 @@ export default class <&classname> extends ApiClient {
       let queryParams = {<#queryParams>
         '<baseName>': <#collectionFormat>this.buildCollectionParam(<#required><paramName></required><^required>opts['<paramName>']</required>, '<collectionFormat>')</collectionFormat><^collectionFormat><#required><paramName></required><^required>opts['<paramName>']</required></collectionFormat><^-last>,</-last></queryParams>
       };
-      let headerParams = {<#headerParams>
+      let headerParams = {
+        'User-Agent': '<#httpUserAgent><.></httpUserAgent><^httpUserAgent>OpenAPI-Generator/<&projectVersion>/Javascript</httpUserAgent>',<#headerParams>
         '<baseName>': <#required><paramName></required><^required>opts['<paramName>']</required><^-last>,</-last></headerParams>
       };
       let formParams = {<#formParams>
diff --git a/modules/openapi-generator/src/main/resources/Javascript/es6/ApiClient.mustache b/modules/openapi-generator/src/main/resources/Javascript/es6/ApiClient.mustache
index c356fd6f45e..a226cfc08aa 100644
--- a/modules/openapi-generator/src/main/resources/Javascript/es6/ApiClient.mustache
+++ b/modules/openapi-generator/src/main/resources/Javascript/es6/ApiClient.mustache
@@ -52,7 +52,9 @@ class ApiClient {
          * @type {Array.<String>}
          * @default {}
          */{{/emitJSDoc}}
-        this.defaultHeaders = {};
+        this.defaultHeaders = {
+            'User-Agent': '{{#httpUserAgent}}{{{.}}}{{/httpUserAgent}}{{^httpUserAgent}}OpenAPI-Generator/{{projectVersion}}/Javascript{{/httpUserAgent}}'
+        };
 
         /**
          * The default HTTP timeout for all API calls.
diff --git a/samples/client/petstore/javascript-es6/src/ApiClient.js b/samples/client/petstore/javascript-es6/src/ApiClient.js
index 4a73394c094..dffe9dda22f 100644
--- a/samples/client/petstore/javascript-es6/src/ApiClient.js
+++ b/samples/client/petstore/javascript-es6/src/ApiClient.js
@@ -53,7 +53,9 @@ class ApiClient {
          * @type {Array.<String>}
          * @default {}
          */
-        this.defaultHeaders = {};
+        this.defaultHeaders = {
+            'User-Agent': 'OpenAPI-Generator/1.0.0/Javascript'
+        };
 
         /**
          * The default HTTP timeout for all API calls.
diff --git a/samples/client/petstore/javascript-promise-es6/src/ApiClient.js b/samples/client/petstore/javascript-promise-es6/src/ApiClient.js
index d5d9e1a7230..c1143615624 100644
--- a/samples/client/petstore/javascript-promise-es6/src/ApiClient.js
+++ b/samples/client/petstore/javascript-promise-es6/src/ApiClient.js
@@ -53,7 +53,9 @@ class ApiClient {
          * @type {Array.<String>}
          * @default {}
          */
-        this.defaultHeaders = {};
+        this.defaultHeaders = {
+            'User-Agent': 'OpenAPI-Generator/1.0.0/Javascript'
+        };
 
         /**
          * The default HTTP timeout for all API calls.