Free Token debugger: Decode, edit and verify JSON Web Tokens, in your browser.

A jwt.io-style debugger for JSON Web Tokens: paste a token to see its header, payload and signature decoded and colour-coded, edit the header or payload to re-encode it live, and verify the HS256 signature against a secret. Everything runs locally; no token ever leaves your browser.

Free, no login, nothing to install. Your work stays in this browser.

What you can do

• Decode a JWT into its header, payload and signature
• Edit the header and payload and re-encode the token live
• Verify an HS256 signature against a secret
• See why the "none" algorithm is a security risk

Graded, AI-assisted versions live in web security and authentication courses.