PAYLOAD:
go install github.com/youruser/jwudtool@latest Got a feature request or found a bug? Open an issue on GitHub .
jwudtool verify --secret mysecret <token> Expected output:
✓ Signature valid If invalid:
"sub": "1234567890", "name": "John Doe", "iat": 1516239022
"alg": "HS256", "typ": "JWT"
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. jwudtool tutorial
Enter — a lightweight, command-line utility designed to simplify JWT inspection, manipulation, and testing.
Happy debugging! This tutorial is for educational purposes only. Only test tokens you own or have permission to analyze.
eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiIxMjM0NTY3ODkwIiwibmFtZSI6IkpvaG4gRG9lIiwiaWF0IjoxNTE2MjM5MDIyfQ.SflKxwRJSMeKKF2QT4fwpMeJf36POk6yJV_adQssw5c Run: PAYLOAD: go install github
jwudtool verify --pubkey public.pem <token> Need to change a claim for testing? Clone and modify:
Mastering JWTs: A Step-by-Step Tutorial to jwudtool
✗ Signature mismatch For RS256 tokens, use a public key: Perfect for developers and security testers