---
source_url: https://www.pubnub.com/docs/serverless/functions/functions-apis/jwt
title: JSON Web Token (JWT)
updated_at: 2026-06-04T11:13:42.785Z
---

> Documentation Index
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> For the full list of all documentation pages, see: https://www.pubnub.com/docs/llms-full.txt


# JSON Web Token (JWT)

[JSON Web Token](https://www.npmjs.com/package/jsonwebtoken) is a library for generating and verifying JSON Web Tokens (JWTs).

The JWT module is available via the following `require()` statement in PubNub Functions:

```javascript
const {sign, decode, verify} = require('jwt');
```

## Exposed methods

Use these methods in your Function code:

* [decode](https://github.com/auth0/node-jsonwebtoken#jwtdecodetoken--options) — Extract the payload and, optionally, the header from a token without verifying its signature.
* [verify](https://github.com/auth0/node-jsonwebtoken#jwtverifytoken-secretorpublickey-options-callback) — Verify a token with a secret or public key and validate expected claims.
* [sign](https://github.com/auth0/node-jsonwebtoken#jwtsignpayload-secretorprivatekey-options-callback) — Create and sign a token from a payload and a secret or private key.

## Examples

### Decode

```js
const jwt = require('jwt');

// Example token (this should be a valid JWT)
const token = 'your.jwt.token.here';

const decoded = jwt.decode(token, { complete: true });
console.log('Decoded Token:', decoded);
```

The `decode` method returns the token’s payload, and if `{ complete: true }` is set, it returns an object containing both the payload and the header.

With `{ complete: true }`:

```text
Decoded Token: {
header: { alg: 'HS256', typ: 'JWT' },
payload: { userId: '123456', username: 'johndoe', iat: 1616239022, exp: 1616242622 },
signature: 'h04J3jUOeGXRHgZzg28pzF5omFxCeK2FlhEXbPZnQ'
}
```

Without `{ complete: true }`:

```text
Decoded Token: { userId: '123456', username: 'johndoe', iat: 1616239022, exp: 1616242622 }
```

### Verify

```js
const jwt = require('jwt');
const secretKey = 'your-256-bit-secret';

// Example token (ensure you replace this with a valid token signed with the `secretKey`)
const token = 'your.jwt.token.here';

try {
const decoded = jwt.verify(token, secretKey);
console.log('Decoded Payload:', decoded);
} catch (err) {
console.error('Token verification failed:', err.message);
}
```

If the token is successfully verified, the `verify` method returns the decoded payload (or the full token data if `complete: true` is specified). If verification fails (due to tampering, expiration, or using the wrong key), it throws an error.

If successful:

```plaintext
Decoded Payload: { userId: '123456', username: 'johndoe', iat: 1616239022, exp: 1616242622 }
```

If verification fails:

```plaintext
Token verification failed: jwt expired
```

The error message will vary depending on the reason for failure, such as expiration or invalid signature.

### Sign

```js
const jwt = require('jwt');

const payload = {
userId: '123456',
username: 'johndoe'
};

const secretKey = 'your-256-bit-secret';

const token = jwt.sign(payload, secretKey, { expiresIn: '1h' });
console.log('Generated Token:', token);
```

The `sign` method returns a JWT as a string. This token can be used in your application for authentication and authorization purposes.

```plaintext
Generated Token: eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJ1c2VySWQiOiIxMjM0NTYiLCJ1c2VybmFtZSI6ImpvaG5kb2UiLCJpYXQiOjE2MTYyMzkwMjIsImV4cCI6MTYxNjI0MjYyMn0.g8h04J3jUOeGXRHgZzg28pzF5omFxCeK2FlhEXbPZnQ
```

The actual token value will differ each time you generate it due to the timestamp and signature.

:::note Functions support
Functions provides a rich set of tools. For help with situations not covered here, contact [PubNub Support](https://www.pubnub.com/docs/mailto:support@pubnub.com).
:::

## Terms in this document

* **PubNub** - PubNub is a real-time messaging platform that provides APIs and SDKs for building scalable applications. It handles the complex infrastructure of real-time communication, including: Message delivery and persistence, Presence detection, Access control, Push notifications, File sharing, Serverless processing with Functions and Events & Actions, Analytics and monitoring with BizOps Workspace, AI-powered insights with Illuminate.