# Verify API keys in your Next.js application with Clerk

When building a resource server that needs to accept and verify API keys issued by Clerk, it's crucial to verify these keys on your backend to ensure the request is coming from an authenticated client.

Clerk's Next.js SDK provides a built-in [auth()](https://clerk.com/docs/reference/nextjs/app-router/auth.md) function that supports token validation via the `acceptsToken` parameter. This lets you specify which type(s) of token your API route should accept. You can also use the [auth.protect()](https://clerk.com/docs/reference/nextjs/app-router/auth.md#auth-protect) method to check if a request includes a valid machine token (e.g. API key or OAuth token) and enforce access rules accordingly.

By default, `acceptsToken` is set to `session_token`, which means API keys will **not** be accepted unless explicitly configured. You can pass either a **single token type** or an **array of token types** to `acceptsToken`. To learn more about the supported token types, see the [auth() parameters documentation](https://clerk.com/docs/reference/nextjs/app-router/auth.md#parameters).

Below are two examples of verifying API keys in a Next.js API route using Clerk's SDK:

## Example 1: Accepting a single token type

In the following example, the `acceptsToken` parameter is set to only accept `api_key`s.

- If the API key is invalid or missing, `auth()` will return `null` for `userId` and other properties, and the request will be rejected with a `401` response.
- If the API key is valid, `userId` and `claims` are returned.

filename: app/api/example/route.ts
```tsx
import { NextResponse } from 'next/server'
import { auth } from '@clerk/nextjs/server'

export async function GET() {
  const { isAuthenticated, claims, userId } = await auth({ acceptsToken: 'api_key' })

  if (!isAuthenticated) {
    return NextResponse.json({ error: 'Unauthorized' }, { status: 401 })
  }

  return NextResponse.json({ userId, claims })
}
```

## Example 2: Accepting multiple token types

In the following example, the `acceptsToken` option allows `session_token`s, `oauth_token`s, and `api_key`s.

- If the token is invalid or missing, `auth()` will return `false` for `isAuthenticated` and `null` for other properties, like `userId`.
- If the token is an `api_key`, the code can access the associated user's data using the `userId`.
- If the token is valid, `isAuthenticated` is `true` and `userId` is returned and available for use in the application logic. This example includes pseudo-code that uses the `userId` to get data from a database.

filename: app/api/example/route.ts
```tsx
import { NextRequest, NextResponse } from 'next/server'
import { auth } from '@clerk/nextjs/server'

export async function POST(req: NextRequest) {
  // Accept session_token, oauth_token, and api_key types
  const { isAuthenticated, tokenType, userId, scopes } = await auth({
    acceptsToken: ['session_token', 'oauth_token', 'api_key'],
  })

  // If the token is invalid or missing
  if (!isAuthenticated) {
    return NextResponse.json({ error: 'Unauthorized' }, { status: 401 })
  }

  // Check if the token is an api key and if it doesn't have the required scope
  if (tokenType === 'api_key' && !scopes?.includes('write:users')) {
    return NextResponse.json({ error: 'API Key missing the "write:users" scope' }, { status: 401 })
  }

  // If the token is valid, move forward with the application logic
  // This example includes pseudo-code for getting data from a database using the userId
  const data = db.select().from(user).where(eq(user.id, userId))

  return NextResponse.json({ data })
}
```

You can also protect entire route groups using [clerkMiddleware()](https://clerk.com/docs/reference/nextjs/clerk-middleware.md). See how to implement this in [the middleware docs](https://clerk.com/docs/reference/nextjs/clerk-middleware.md#protect-routes-based-on-token-types).

---

## Sitemap

[Overview of all docs pages](https://clerk.com/docs/llms.txt)