Auth.js (NextAuth) authentication

Using Auth.js (NextAuth) as your authentication service.

NextAuth is a popular authentication solution for Next.js applications. It supports many different authentication providers and is easy to configure.

NextAuth v5 is the default authentication provider for the Next.js starter kit and is configured with the Resend email provider out of the box.

Configure

The NextAuth configuration is located in packages/auth-authjs and is split up into two files:

  • config.ts - The edge compatible configuration, used in Next.js middleware.
  • auth.ts - The main NextAuth configuration.

Please refer to the NextAuth documentation for more information on how to configure NextAuth.

Add a new provider

To add a new authentication provider, here is an example of how to add Google as an authentication provider:

Edit the auth.ts file to add the new provider:

// packages/auth-authjs/src/auth.ts
import GoogleProvider from 'next-auth/providers/google'


// ... existing code
  providers: [
    // ... existing providers
    GoogleProvider({
      clientId: env.GOOGLE_CLIENT_ID,
      clientSecret: .GOOGLE_CLIENT_SECRET,
    }),
  ],
// ... existing code

Note that we are using the env object to get the client ID and secret from the environment variables. This way we can ensure that the client ID and secret are set and available at runtime.

// packages/auth-authjs/src/env.ts
import { createEnv } from 'env/create'
import { z } from 'zod'


export const env = createEnv(
  z.object({
    AUTH_DEBUG: z.coerce.boolean().optional(),
    AUTH_SECRET: z.string(),
    EMAIL_FROM: z.string(),
    GOOGLE_CLIENT_ID: z.string(),
    GOOGLE_CLIENT_SECRET: z.string(),
  })
)

After adding the new provider, you can add the new environment variables to the .env file.

// .env
GOOGLE_CLIENT_ID=<your-client-id>
GOOGLE_CLIENT_SECRET=<your-client-secret>

Now you can add the new provider to your authenication screens. Refer to the customize auth screens documentation for more information.

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