JWT Decoder
A secure way to inspect digital tokens (JWT) and see exactly what information they contain. Everything happens locally, ensuring your sensitive identity data never leaves your computer.
Deep Dive
Our JWT Decoder & Debugger is a professional-grade tool designed for developers who need to inspect, validate, and debug JSON Web Tokens without compromising security.
Unlike online tools that send your sensitive tokens to their servers, our debugger executes 100% locally. Your secrets and payloads never leave your browser, providing a sandbox for verification and debugging.
Why Use Our Debugger?
Zero-Data Privacy
We never store or log your tokens. Processing is strictly client-side.
Native Signature
Verify HMAC signatures instantly using browser-native SubtleCrypto.
Claim Inspection
Identify standard claims like iat, exp, and sub with human-readable dates.
Mobile Optimized
Debug on the go with a responsive UI that adapts to any screen size.
Pro-Grade Capabilities
Advanced features for secure JWT debugging and identity management.
Real-time Decoding
Instant breakdown of Header, Payload, and Signature parts.
HMAC Verification
Verify token integrity with your local 256-bit secrets.
Expiry Validation
Visual warnings for expired (exp) or not-yet-valid (nbf) tokens.
Syntax Highlighting
Beautiful JSON formatting for complex nested payloads.
Claim Explainers
Built-in guides for standard registered JWT claims.
Privacy Sandbox
No server-side calls — tokens never transit the internet.
Base64 Support
Handles both Base64 and Base64Url encoding standards.
Compact Headers
Identify 'alg' and 'typ' parameters at a glance.
Signature Debugging
Verify how signature behaves as you modify the payload.
Export JSON
Copy formatted payload objects for use in your test suites.
Common Questions
Is it safe to paste my JWT?
Absolutely. This tool is client-side only. We use JavaScript to decode and verify signatures directly in your browser. No data is sent to our servers.
Can I verify RSA/ECDSA signatures?
Currently, the debugger focuses on HMAC-SHA (Symmetric) algorithms. support for RSA public keys (Asymmetric) is planned for the next Pro update.
Why doesn't the signature verify?
Verification fails if the secret key is incorrect or if the token has been tampered with. Check that your secret matches the issuer's key exactly.
Client-Side Only · Secure Sandbox · W3C Crypto Standard
How to Debug JWTs
- 1
Paste your Encoded JWT into the primary text area.
- 2
Instant breakdown of Header/Payload will appear automatically.
- 3
Check for the 'exp' claim to verify if the token is still valid.
- 4
Input your Secret Key to verify the HMAC signature.
- 5
View real-time status: Verified or Invalid Signature.