Serving Angular apps for development

You can serve your Angular CLI application with the ng serve command. This will compile your application, skip unnecessary optimizations, start a devserver, and automatically rebuild and live reload any subsequent changes. You can stop the server by pressing Ctrl+C.

ng serve only executes the builder for the serve target in the default project as specified in angular.json. While any builder can be used here, the most common (and default) builder is @angular-devkit/build-angular:dev-server.

You can determine which builder is being used for a particular project by looking up the serve target for that project.

      
{  "projects": {    "my-app": {      "architect": {        // `ng serve` invokes the Architect target named `serve`.        "serve": {          "builder": "@angular-devkit/build-angular:dev-server",          // ...        },        "build": { /* ... */ }        "test": { /* ... */ }      }    }  }}
    

This page discusses usage and options of @angular-devkit/build-angular:dev-server.

Proxying to a backend server

Use proxying support to divert certain URLs to a backend server, by passing a file to the --proxy-config build option. For example, to divert all calls for http://localhost:4200/api to a server running on http://localhost:3000/api, take the following steps.

1. Create a file proxy.conf.json in your project's src/ folder.

2. Add the following content to the new proxy file:

         
   {   "/api": {     "target": "http://localhost:3000",     "secure": false   } }
       

3. In the CLI configuration file, angular.json, add the proxyConfig option to the serve target:

         
   {   "projects": {     "my-app": {       "architect": {         "serve": {           "builder": "@angular-devkit/build-angular:dev-server",           "options": {             "proxyConfig": "src/proxy.conf.json"           }         }       }     }   } }
       

4. To run the development server with this proxy configuration, call ng serve.

Edit the proxy configuration file to add configuration options; following are some examples. For a detailed description of all options, refer to the webpack DevServer documentation when using @angular-devkit/build-angular:browser, or the Vite DevServer documentation when using @angular-devkit/build-angular:browser-esbuild or @angular-devkit/build-angular:application.

NOTE: If you edit the proxy configuration file, you must relaunch the ng serve process to make your changes effective.

localhost resolution

As of Node version 17, Node will not always resolve http://localhost:<port> to http://127.0.0.1:<port> depending on each machine's configuration.

If you get an ECONNREFUSED error using a proxy targeting a localhost URL, you can fix this issue by updating the target from http://localhost:<port> to http://127.0.0.1:<port>.

See the http-proxy-middleware documentation for more information.