Offline JWT Debugger
Decode and inspect JSON Web Tokens instantly.
Encoded Token
Decoded Output
{}{}Signature will appear here...
Frequently Asked Questions
Is it safe to decode JWTs on this site?
Yes. KNothing's JWT Debugger runs **100% client-side**. Your tokens (and secrets) **never leave your browser**, preventing any server-side logging leaks. It's a secure alternative to jwt.io for sensitive production tokens.
Can I decode JWTs without internet?
Yes. This tool is **offline-capable**. Once loaded, you can decode tokens even in an **air-gapped environment** or when you have no network connection.
Does it verify the signature?
Currently, it focuses on **decoding the Header and Payload** for debugging. Verification features are planned, but we prioritize privacy by not asking for your private keys.
What is a JSON Web Token (JWT)?
A JSON Web Token (JWT) is an open standard (RFC 7519) that defines a compact and self-contained way for securely transmitting information between parties as a JSON object, often used for **authentication and information exchange**.
How do I debug a JWT expiration (exp) issue?
Our debugger automatically converts the **exp (expiration time)** and **iat (issued at)** timestamps into **human-readable dates**, making it easy to identify why a token might be invalid or expired.