Tiny Toolkit

JWT Decoder

Paste a JSON Web Token to decode and inspect its header, payload, and expiry — entirely in your browser with no server calls. The tool highlights whether the token has expired and formats the JSON claims for easy reading. Useful for debugging authentication flows, inspecting tokens returned by APIs, and understanding what claims are being passed around your system.

All processing happens in your browser. No data is sent to any server.

Frequently Asked Questions

What is a JWT?
A JSON Web Token (JWT) is a compact, URL-safe token used for authentication and information exchange. It consists of three Base64URL-encoded parts (header, payload, and signature), separated by dots.
Does this tool verify the JWT signature?
No. It only decodes and displays the contents. Signature verification requires the secret key and must be done server-side in a trusted environment.
Is it safe to paste my tokens into this tool?
All decoding happens in your browser with no server calls. That said, treat JWTs like passwords; avoid pasting real production tokens into any online tool.

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Related Articles

What Is a JWT? JSON Web Tokens Explained

A JWT is a compact, URL-safe token used for authentication and data exchange. Here's how the three-part structure works, what each part contains, and how to inspect one.

5 min read