better-auth/docs/content/docs/plugins/jwt.mdx

---
title: JWT
description: Authenticate users with JWT tokens in services that can't use the session
---

The JWT plugin provides endpoints to retrieve a JWT token and a JWKS endpoint to verify the token.

<Callout type="info">
  This plugin is not meant as a replacement for the session. It's meant to be used for services that require JWT tokens. If you're looking to use JWT tokens for authentication, check out the [Bearer Plugin](/docs/plugins/bearer).
</Callout>

## Installation

<Steps>
<Step>
### Add the plugin to your **auth** config
```ts title="auth.ts"
import { betterAuth } from "better-auth"
import { jwt } from "better-auth/plugins"

export const auth = betterAuth({
    plugins: [ // [!code highlight]
        jwt(), // [!code highlight]
    ] // [!code highlight]
})
```
</Step>

<Step>
    ### Migrate the database

    Run the migration or generate the schema to add the necessary fields and tables to the database.

    <Tabs items={["migrate", "generate"]}>
        <Tab value="migrate">
        ```bash
        npx @better-auth/cli migrate
        ```
        </Tab>
        <Tab value="generate">
        ```bash
        npx @better-auth/cli generate
        ```
        </Tab>
    </Tabs>
    See the [Schema](#schema) section to add the fields manually.
</Step>
</Steps>    


## Usage

Once you've installed the plugin, you can start using the JWT & JWKS plugin to get the token and the JWKS through their respective endpoints.

## JWT

### Retrieve the token

There are multiple ways to retrieve JWT tokens:

1. **Using the client plugin (recommended)**

Add the `jwtClient` plugin to your auth client configuration:

```ts title="auth-client.ts"
import { createAuthClient } from "better-auth/client"
import { jwtClient } from "better-auth/client/plugins" // [!code highlight]

export const authClient = createAuthClient({
  plugins: [
    jwtClient() // [!code highlight]
  ]
})
```

Then use the client to get JWT tokens:

```ts
const { data, error } = await authClient.token()
if (error) {
  // handle error
}
if (data) {
  const jwtToken = data.token
  // Use this token for authenticated requests to external services
}
```

This is the recommended approach for client applications that need JWT tokens for external API authentication.

2. **Using your session token**

To get the token, call the `/token` endpoint. This will return the following:
  
```json
  { 
    "token": "ey..."
  }
```

Make sure to include the token in the `Authorization` header of your requests if the `bearer` plugin is added in your auth configuration.

```ts
await fetch("/api/auth/token", {
  headers: {
    "Authorization": `Bearer ${token}`
  },
})
```

3. **From `set-auth-jwt` header**

When you call `getSession` method, a JWT is returned in the `set-auth-jwt` header, which you can use to send to your services directly.

```ts
await authClient.getSession({
  fetchOptions: {
    onSuccess: (ctx)=>{
      const jwt = ctx.response.headers.get("set-auth-jwt")
    }
  }
})
```

### Verifying the token
The token can be verified in your own service, without the need for an additional verify call or database check.
For this JWKS is used. The public key can be fetched from the `/api/auth/jwks` endpoint.

Since this key is not subject to frequent changes, it can be cached indefinitely.
The key ID (`kid`) that was used to sign a JWT is included in the header of the token.
In case a JWT with a different `kid` is received, it is recommended to fetch the JWKS again.

```json
  {
    "keys": [
        {
            "crv": "Ed25519",
            "x": "bDHiLTt7u-VIU7rfmcltcFhaHKLVvWFy-_csKZARUEU",
            "kty": "OKP",
            "kid": "c5c7995d-0037-4553-8aee-b5b620b89b23"
        }
    ]
  }
```

### OAuth Provider Mode

If you are making your system oAuth compliant (such as when utilizing the OIDC or MCP plugins), you **MUST** disable the `/token` endpoint (oAuth equivalent `/oauth2/token`) and disable setting the jwt header (oAuth equivalent `/oauth2/userinfo`).

```ts title="auth.ts"
betterAuth({
  disabledPaths: [
    "/token",
  ],
  plugins: [jwt({
    disableSettingJwtHeader: true,
  })]
})
```

#### Example using jose with remote JWKS

```ts
import { jwtVerify, createRemoteJWKSet } from 'jose'

async function validateToken(token: string) {
  try {
    const JWKS = createRemoteJWKSet(
      new URL('http://localhost:3000/api/auth/jwks')
    )
    const { payload } = await jwtVerify(token, JWKS, {
      issuer: 'http://localhost:3000', // Should match your JWT issuer, which is the BASE_URL
      audience: 'http://localhost:3000', // Should match your JWT audience, which is the BASE_URL by default
    })
    return payload
  } catch (error) {
    console.error('Token validation failed:', error)
    throw error
  }
}

// Usage example
const token = 'your.jwt.token' // this is the token you get from the /api/auth/token endpoint
const payload = await validateToken(token)
```

#### Example with local JWKS

```ts
import { jwtVerify, createLocalJWKSet } from 'jose'


async function validateToken(token: string) {
  try {
    /**
     * This is the JWKS that you get from the /api/auth/
     * jwks endpoint
     */
    const storedJWKS = {
      keys: [{
        //...
      }]
    };
    const JWKS = createLocalJWKSet({
      keys: storedJWKS.data?.keys!,
    })
    const { payload } = await jwtVerify(token, JWKS, {
      issuer: 'http://localhost:3000', // Should match your JWT issuer, which is the BASE_URL
      audience: 'http://localhost:3000', // Should match your JWT audience, which is the BASE_URL by default
    })
    return payload
  } catch (error) {
    console.error('Token validation failed:', error)
    throw error
  }
}

// Usage example
const token = 'your.jwt.token' // this is the token you get from the /api/auth/token endpoint
const payload = await validateToken(token)
```

### Remote JWKS Url

Disables the `/jwks` endpoint and uses this endpoint in any discovery such as OIDC.

Useful if your JWKS are not managed at `/jwks` or if your jwks are signed with a certificate and placed on your CDN.

NOTE: you **MUST** specify which asymmetric algorithm is used for signing.

```ts title="auth.ts"
jwt({
  jwks: {
    remoteUrl: "https://example.com/.well-known/jwks.json",
    keyPairConfig: {
      alg: 'ES256',
    },
  }
})
```

### Custom Signing

This is an advanced feature. Configuration outside of this plugin **MUST** be provided.

Implementers:
- `remoteUrl` must be defined if using the `sign` function. This shall store all active keys, not just the current one.
- If using localized approach, ensure server uses the latest private key when rotated. Depending on deployment, the server may need to be restarted.
- When using remote approach, verify the payload is unchanged after transit. Use integrity validation like CRC32 or SHA256 checks if available.

#### Localized Signing

```ts title="auth.ts"
jwt({
  jwks: {
    remoteUrl: "https://example.com/.well-known/jwks.json",
    keyPairConfig: {
      alg: 'EdDSA',
    },
  },
  jwt: {
    sign: async (jwtPayload: JWTPayload) => {
      // this is pseudocode
      return await new SignJWT(jwtPayload)
        .setProtectedHeader({
          alg: "EdDSA",
          kid: process.env.currentKid,
          typ: "JWT",
        })
        .sign(process.env.clientPrivateKey);
    },
  },
})
```

#### Remote Signing

Useful if you are using a remote Key Management Service such as [Google KMS](https://cloud.google.com/kms/docs/encrypt-decrypt-rsa#kms-encrypt-asymmetric-nodejs), [Amazon KMS](https://docs.aws.amazon.com/kms/latest/APIReference/API_Sign.html), or [Azure Key Vault](https://learn.microsoft.com/en-us/rest/api/keyvault/keys/sign/sign?view=rest-keyvault-keys-7.4&tabs=HTTP).

```ts title="auth.ts"
jwt({
  jwks: {
    remoteUrl: "https://example.com/.well-known/jwks.json",
    keyPairConfig: {
      alg: 'ES256',
    },
  },
  jwt: {
    sign: async (jwtPayload: JWTPayload) => {
      // this is pseudocode
      const headers = JSON.stringify({ kid: '123', alg: 'ES256', typ: 'JWT' })
      const payload = JSON.stringify(jwtPayload)
      const encodedHeaders = Buffer.from(headers).toString('base64url')
      const encodedPayload = Buffer.from(payload).toString('base64url')
      const hash = createHash('sha256')
      const data = `${encodedHeaders}.${encodedPayload}`
      hash.update(Buffer.from(data))
      const digest = hash.digest()
      const sig = await remoteSign(digest)
      // integrityCheck(sig)
      const jwt = `${data}.${sig}`
      // verifyJwt(jwt)
      return jwt
    },
  },
})
```


## Schema

The JWT plugin adds the following tables to the database:

### JWKS

Table Name: `jwks`

<DatabaseTable
  fields={[
    { 
      name: "id", 
      type: "string", 
      description: "Unique identifier for each web key",
      isPrimaryKey: true
    },
    { 
      name: "publicKey", 
      type: "string", 
      description: "The public part of the web key" 
    },
    { 
      name: "privateKey", 
      type: "string", 
      description: "The private part of the web key" 
    },
    { 
      name: "createdAt", 
      type: "Date", 
      description: "Timestamp of when the web key was created" 
    },
  ]}
  />

<Callout>
  You can customize the table name and fields for the `jwks` table. See the [Database concept documentation](/docs/concepts/database#custom-table-names) for more information on how to customize plugin schema.
</Callout>

## Options

### Algorithm of the Key Pair

The algorithm used for the generation of the key pair. The default is **EdDSA** with the **Ed25519** curve. Below are the available options:

```ts title="auth.ts"
jwt({
  jwks: {
    keyPairConfig: {
      alg: "EdDSA",
      crv: "Ed25519"
    }
  }
})
```

#### EdDSA
- **Default Curve**: `Ed25519`
- **Optional Property**: `crv`
  - Available options: `Ed25519`, `Ed448`
  - Default: `Ed25519`

#### ES256
- No additional properties

#### RSA256
- **Optional Property**: `modulusLength`
  - Expects a number
  - Default: `2048`

#### PS256
- **Optional Property**: `modulusLength`
  - Expects a number
  - Default: `2048`

#### ECDH-ES
- **Optional Property**: `crv`
  - Available options: `P-256`, `P-384`, `P-521`
  - Default: `P-256`

#### ES512
- No additional properties


### Disable private key encryption

By default, the private key is encrypted using AES256 GCM. You can disable this by setting the `disablePrivateKeyEncryption` option to `true`.

For security reasons, it's recommended to keep the private key encrypted.

```ts title="auth.ts"
jwt({
  jwks: {
    disablePrivateKeyEncryption: true
  }
})
```

### Modify JWT payload

By default the entire user object is added to the JWT payload. You can modify the payload by providing a function to the `definePayload` option.

```ts title="auth.ts"
jwt({
  jwt: {
    definePayload: ({user}) => {
      return {
        id: user.id,
        email: user.email,
        role: user.role
      }
    }
  }
})
```

### Modify Issuer, Audience, Subject or Expiration time
If none is given, the `BASE_URL` is used as the issuer and the audience is set to the `BASE_URL`. The expiration time is set to 15 minutes.

```ts title="auth.ts"
jwt({
  jwt: {
    issuer: "https://example.com",
    audience: "https://example.com",
    expirationTime: "1h",
    getSubject: (session) => {
      // by default the subject is the user id
      return session.user.email
    }
  }
})
```

### Custom Adapter

By default, the JWT plugin stores and retrieves JWKS from your database. You can provide a custom adapter to override this behavior, allowing you to store JWKS in alternative locations such as Redis, external services, or in-memory storage.

```ts title="auth.ts"
jwt({
  adapter: {
    getJwks: async (ctx) => {
      // Custom implementation to get all JWKS
      // This overrides the default database query
      return await yourCustomStorage.getAllKeys()
    },
    getLatestKey: async (ctx) => {
      // Custom implementation to get the latest key
      // This overrides the default database query
      return await yourCustomStorage.getLatestKey()
    },
    createJwk: async (ctx, webKey) => {
      // Custom implementation to create a new key
      // This overrides the default database insert
      return await yourCustomStorage.createKey(webKey)
    }
  }
})
```