JWT Encoder

About this tool

This JWT encoder helps you build a JSON Web Token quickly and safely without sending any data to a server. It is useful when you need a test token for an API, want to learn how JWTs are structured, or need to generate a signed token for a development environment. Everything runs in your browser, so secrets and keys stay on your device.

A JWT has three parts separated by dots: the header, the payload, and the signature. The header describes the signing algorithm, the payload holds claims such as user IDs or roles, and the signature proves that the token was created by a trusted party. The header and payload are JSON that get Base64URL-encoded; the signature is created by signing the exact string header.payload. Changing even one character changes the signature.

To use this tool, enter your header and payload JSON in the input fields. Choose the signing method that matches your system, then provide a secret or private key if needed. Click Generate, and the full token appears instantly. You can copy the encoded JWT into your application, Postman, or a test request.

Signing options cover common use cases. HS256 uses a shared secret string and is common for internal services. RS256 uses an RSA private key to sign and a public key to verify, which is better when multiple services need to validate tokens without sharing a secret. The none option creates an unsigned token for debugging only and should not be used in production.

Real-world examples include generating access tokens for API testing, creating short-lived tokens with expiration claims, or simulating login flows while building an authentication system. Whether you need a JWT generator, a JSON Web Token encoder, or a quick way to sign payloads, this tool provides a clear, reliable workflow.

Everything happens locally using the Web Crypto API. For highly sensitive keys, consider using the offline bundle or a dedicated local environment.