JWT Decoder & Debugger
Decode and debug JSON Web Tokens (JWT) instantly. View decoded header and payload, verify token structure, and understand JWT claims. Perfect for developers working with authentication.
- Tokens never leave your device
- No server upload required
- Works completely offline
- No login or signup needed
How It Works
Paste a JWT token into the input field and the tool automatically decodes it into three parts: header, payload, and signature. The header and payload are Base64-decoded and displayed as formatted JSON. You can see all claims, expiration times, and token metadata. The tool validates the token structure and shows if it's properly formatted. All decoding happens in your browser — your tokens are never sent to any server. Perfect for debugging authentication issues, understanding token contents, and verifying JWT structure.
Frequently Asked Questions
What is a JWT token?
JWT (JSON Web Token) is a compact, URL-safe token format used for securely transmitting information between parties. It's commonly used for authentication and authorization.
What are the three parts of a JWT?
A JWT consists of three parts separated by dots: Header (algorithm and token type), Payload (claims and data), and Signature (verification).
Can this tool verify JWT signatures?
This tool decodes and displays JWT contents. Signature verification requires the secret key, which should never be shared or entered into online tools.
Is it safe to decode my JWT here?
Yes! All decoding happens in your browser. The token is never sent to any server. However, avoid pasting production tokens with sensitive data on any public computer.
Why can't I decode my token?
Make sure you're pasting the complete JWT token with all three parts (header.payload.signature). The token should not have any extra spaces or characters.