# Fastify Quickstart

**Example Repository**

- [Fastify Quickstart Repo](https://github.com/clerk/clerk-fastify-quickstart)

**Before you start**

- [Set up a Clerk application](https://clerk.com/docs/getting-started/quickstart/setup-clerk.md?sdk=fastify)
- [Add Fastify as your backend](https://fastify.dev/docs/latest/Guides/Getting-Started)

Learn how to integrate Clerk into your Fastify backend for secure user authentication and management. This guide uses TypeScript and allows you to choose your frontend framework.

> [Fastify is only compatible with Next.js versions 13.4 and below](https://github.com/fastify/fastify-nextjs). If you're using a newer version of Next.js, consider using a different backend framework that supports the latest Next.js features.
>
> This guide uses ECMAScript Modules (ESM). To use ESM in your project, you must include `"type": "module"` in your `package.json`.

1. ## Install `@clerk/fastify`

   The [Clerk Fastify SDK](https://clerk.com/docs/fastify/reference/fastify/overview.md) provides a range of backend utilities to simplify user authentication and management in your application.

   Run the following command to install the SDK:

   ```npm
   npm install @clerk/fastify
   ```
2. ## Set your Clerk API keys

   Add the following keys to your `.env` file. These keys can always be retrieved from the [**API keys**](https://dashboard.clerk.com/~/api-keys) page in the Clerk Dashboard.

   1. In the Clerk Dashboard, navigate to the [**API keys**](https://dashboard.clerk.com/~/api-keys) page.
   2. In the **Quick Copy** section, copy your Clerk Publishable Key and Secret Key.
   3. Paste your keys into your `.env` file.

   The final result should resemble the following:

   filename: .env

   ```env
   CLERK_PUBLISHABLE_KEY={{pub_key}}
   CLERK_SECRET_KEY={{secret}}
   ```
3. ## Configure `clerkPlugin()` for all routes

   The [clerkPlugin()](https://clerk.com/docs/fastify/reference/fastify/clerk-plugin.md) function is a Fastify plugin provided by Clerk to integrate authentication into your Fastify application. To ensure that Clerk's authentication and user management features are applied across your Fastify application, configure the `clerkPlugin()` to handle all routes or limit it to specific ones.

   The following example registers the plugin for all routes. To register the plugin for specific routes, see the [reference docs](https://clerk.com/docs/fastify/reference/fastify/overview.md).

   > Load environment variables before importing any Clerk modules. Clerk reads environment variables (such as API keys) during initialization, so they must be available at import time.
   >
   > In Node.js, run your app with the `--env-file=.env` flag so environment variables are available during module initialization.
   >
   > For more information, refer to the [Fastify docs](https://fastify.dev/docs/latest/Guides/Getting-Started/#loading-order-of-your-plugins).

   filename: index.ts

   ```ts
   import Fastify from 'fastify'
   import { clerkPlugin } from '@clerk/fastify'

   const fastify = Fastify({ logger: true })

   fastify.register(clerkPlugin)

   const start = async () => {
     try {
       await fastify.listen({ port: 8080 })
     } catch (error) {
       fastify.log.error(error)
       process.exit(1)
     }
   }

   start()
   ```
4. ## Protect your routes using `getAuth()`

   The [getAuth()](https://clerk.com/docs/fastify/reference/fastify/get-auth.md) helper retrieves the current user's authentication state from the `request` object. It returns the [`Auth` object](https://clerk.com/docs/reference/backend/types/auth-object.md?sdk=fastify){{ target: '_blank' }}.

   The following example uses `getAuth()` to protect a route and load the user's data. If the user is authenticated, their `userId` is passed to [`clerkClient.users.getUser()`](https://clerk.com/docs/reference/backend/user/get-user.md?sdk=fastify){{ target: '_blank' }} to get the current user's [User](https://clerk.com/docs/reference/objects/user.md){{ target: '_blank' }} object. If not authenticated, the request is rejected with a `401` status code.

   ```ts
   import Fastify from 'fastify'
   import { clerkClient, clerkPlugin, getAuth } from '@clerk/fastify'

   const fastify = Fastify({ logger: true })

   fastify.register(clerkPlugin)

   // Use `getAuth()` to protect this route
   fastify.get('/protected', async (request, reply) => {
     try {
       // Use `getAuth()` to access `isAuthenticated` and the user's ID
       const { isAuthenticated, userId } = getAuth(request)

       // If user isn't authenticated, return a 401 error
       if (!isAuthenticated) {
         return reply.code(401).send({ error: 'User not authenticated' })
       }

       // Use `clerkClient` to access the `getUser()` method to get the user's User object
       const user = await clerkClient.users.getUser(userId)

       return reply.send({
         message: 'User retrieved successfully',
         user,
       })
     } catch (error) {
       fastify.log.error(error)
       return reply.code(500).send({ error: 'Failed to retrieve user' })
     }
   })

   const start = async () => {
     try {
       await fastify.listen({ port: 8080 })
     } catch (error) {
       fastify.log.error(error)
       process.exit(1)
     }
   }

   start()
   ```

## Next steps

Learn how to protect routes, handle authentication and authorization, and prepare your Clerk app for production using the following guides.

- [Protect routes using clerkPlugin()](https://clerk.com/docs/reference/fastify/clerk-plugin.md?sdk=fastify): Learn how to protect specific routes from unauthenticated users.
- [Protect routes based on authorization status](https://clerk.com/docs/reference/fastify/get-auth.md?sdk=fastify): Learn how to protect a route based on both authentication and authorization status.
- [Deploy to production](https://clerk.com/docs/guides/development/deployment/production.md?sdk=fastify): Learn how to deploy your Clerk app to production.
- [Clerk Fastify SDK reference](https://clerk.com/docs/reference/fastify/overview.md?sdk=fastify): Learn about the Clerk Fastify SDK and how to integrate it into your app.

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## Sitemap

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