Jwudtool Tutorial (2025)

PAYLOAD:

Happy debugging! This tutorial is for educational purposes only. Only test tokens you own or have permission to analyze.

jwudtool verify --secret mysecret <token> Expected output: jwudtool tutorial

go install github.com/youruser/jwudtool@latest Got a feature request or found a bug? Open an issue on GitHub .

Mastering JWTs: A Step-by-Step Tutorial to jwudtool PAYLOAD: Happy debugging

💡 Tip: Use --pretty for colorized output. If you have the secret key ( mysecret ):

HEADER:

"sub": "1234567890", "name": "John Doe", "iat": 1516239022

jwudtool version # Output: jwudtool 0.2.0 | Command | Purpose | |---------|---------| | decode | Decode header + payload without verifying signature | | verify | Check signature using a secret or public key | | forge | Create a new token from an existing one (change claims) | | fuzz | Test token against common attacks | Tutorial: Decode a JWT Given this sample token: If you have the secret key ( mysecret

✗ Signature mismatch For RS256 tokens, use a public key:

Learn how to decode, verify, and debug JSON Web Tokens using jwudtool. Perfect for developers and security testers. Introduction JSON Web Tokens (JWTs) are everywhere — from authentication flows to API authorization. But if you’ve ever tried to manually decode a JWT or debug a signature mismatch, you know it can get messy fast.