JWT Debugger

JWT Debugger is a free online tool for decoding, verifying, and debugging JSON Web Tokens (JWT). Inspect header and payload claims, verify signatures with secret keys, validate token expiration, and understand JWT structure instantly.

Built with modern web technologies, this tool processes JWTs entirely in your browser with client-side validation, ensuring your tokens and secrets remain private and secure without server transmission.

This tool simplifies JWT authentication debugging and token inspection. Quickly decode tokens to view claims, verify signatures to ensure authenticity, check expiration times, and troubleshoot authentication issues without writing code.

Perfect for backend developers, security engineers, API developers, and anyone implementing JWT authentication who needs to debug tokens, validate signatures, and understand token contents instantly.

Authentication Debugging: Decode JWTs to inspect user claims, verify token contents, and troubleshoot authentication failures in applications.

Signature Verification: Validate JWT signatures using secret keys or public keys to ensure token authenticity and prevent tampering.

Token Analysis: Examine JWT structure, understand header algorithms, inspect payload claims, and verify token expiration times.

Development & Testing: Test JWT generation, validate token formats, and ensure proper claim structure during API development.

Paste your JWT token into the encoded field. The tool automatically decodes and displays the header and payload sections with syntax highlighting.

To verify the signature, enter your secret key or public key in the verification section. The tool validates the signature and indicates whether the token is authentic and hasn't been tampered with.