Set up local development for Azure Static Web Apps

When published to the cloud, an Azure Static Web Apps site links together many services that work together as if they're the same application. These services include:

  • The static web app
  • Azure Functions API
  • Authentication and authorization services
  • Routing and configuration services

These services must communicate with each other, and Azure Static Web Apps handles this integration for you in the cloud.

Running locally, however, these services aren't automatically tied together.

To provide a similar experience as to what you get in Azure, the Azure Static Web Apps CLI provides the following services:

  • A local static site server
  • A proxy to the front-end framework development server
  • A proxy to your API endpoints - available through Azure Functions Core Tools
  • A mock authentication and authorization server
  • Local routes and configuration settings enforcement


Often sites built with a front-end framework require a proxy configuration setting to correctly handle requests under the api route. When using the Azure Static Web Apps CLI the proxy location value is /api, and without the CLI the value is http://localhost:7071/api.

How it works

The following chart shows how requests are handled locally.

Azure Static Web App CLI request and response flow


Navigate to http://localhost:4280 to access the application served by the CLI.

  • Requests made to port 4280 are forwarded to the appropriate server depending on the type of request.

  • Static content requests, such as HTML or CSS, are either handled by the internal CLI static content server, or by the front-end framework server for debugging.

  • Authentication and authorization requests are handled by an emulator, which provides a fake identity profile to your app.

  • Functions Core Tools runtime handles requests to the site's API.

  • Responses from all services are returned to the browser as if they were all a single application.


  • Existing Azure Static Web Apps site: If you don't have one, begin with the vanilla-api starter app.
  • Node.js with npm: Run the Node.js LTS version, which includes access to npm.
  • Visual Studio Code: Used for debugging the API application, but not required for the CLI.


In order to run swa with an API locally, the Azure Functions Core Tools are required.

Get started

Open a terminal to the root folder of your existing Azure Static Web Apps site.

  1. Install the CLI.

    npm install -g @azure/static-web-apps-cli

  2. Build your app if required by your application.

    Run npm run build, or the equivalent command for your project.

  3. Change into the output directory for your app. Output folders are often named build or something similar.

  4. Start the CLI.

    swa start

  5. Navigate to http://localhost:4280 to view the app in the browser.

Other ways to start the CLI

Description Command
Serve a specific folder swa start ./output-folder
Use a running framework development server swa start http://localhost:3000
Start a Functions app in a folder swa start ./output-folder --api ./api
Use a running Functions app swa start ./output-folder --api http://localhost:7071

Authorization and authentication emulation

The Static Web Apps CLI emulates the security flow implemented in Azure. When a user logs in, you can define a fake identity profile returned to the app.

For instance, when you try to navigate to /.auth/login/github, a page is returned that allows you to define an identity profile.


The emulator works with any security provider, not just GitHub.

Local authentication and authorization emulator

The emulator provides a page allowing you to provide the following client principal values:

Value Description
Username The account name associated with the security provider. This value appears as the userDetails property in the client principal and is autogenerated if you don't provide a value.
User ID Value autogenerated by the CLI.
Roles A list of role names, where each name is on a new line.

Once logged in:

  • You can use the /.auth/me endpoint, or a function endpoint to retrieve the user's client principal.

  • Navigating to /.auth/logout clears the client principal and logs out the mock user.


There are two debugging contexts in a static web app. The first is for the static content site, and the second is for API functions. Local debugging is possible by allowing the Static Web Apps CLI to use development servers for one or both of these contexts.

The following steps show you a common scenario that uses development servers for both debugging contexts.

  1. Start the static site development server. This command is specific to the front-end framework you're using, but often comes in the form of commands like npm run build, npm start, or npm run dev.

  2. Open the API application folder in Visual Studio Code and start a debugging session.

  3. Pass the addresses for the static server and API server to the swa start command by listing them in order.

    swa start http://localhost:<DEV-SERVER-PORT-NUMBER> --api=http://localhost:7071

The following screenshots show the terminals for a typical debugging scenario:

The static content site is running via npm run dev.

Static site development server

The Azure Functions API application is running a debug session in Visual Studio Code.

Visual Studio Code API debugging

The Static Web Apps CLI is launched using both development servers.

Azure Static Web Apps CLI terminal

Now requests that go through port 4280 are routed to either the static content development server, or the API debugging session.

For more information on different debugging scenarios, with guidance on how to customize ports and server addresses, see the Azure Static Web Apps CLI repository.

Next steps