JWT Debugger
Decode and inspect JWT tokens locally
Ready to decode
Paste a JWT in the input box to verify its contents
Private & Secure JWT Debugger: Decode Tokens Client-Side
Decode, inspect, and verify JSON Web Tokens (JWTs) without sending secrets to a server. Our offline-first JWT Debugger parses header and payload data directly in your browser, guaranteeing that sensitive auth tokens never leave your device.
Core Features for Security Engineers
Zero Server TransmissionStandard debuggers require you to paste tokens into a form. We implement the entire JOSE standard locally.
Claim InspectionFormatted, color-coded JSON view of standard claims (`iss`, `sub`, `aud`) to catch auth bugs fast.
Expiration AnalysisVisual countdowns for `exp` and `nbf` claims to verify session timeouts and validity windows.
Local Signature ValidationVerify HS256/RS256 signatures using secrets kept strictly in your browser's memory.
How It Works
- Paste Token: Input your JSON Web Token (JWT) into the encoded field.
- Auto-Decode: The tool instantly parses the Header, Payload, and Signature.
- Inspect Claims: View decoded claims like `sub`, `iat`, and `exp` in a readable format.
- Verify Signature: Enter your secret key to verify if the token is valid and untampered.
Privacy Protocol: No Leaked Keys
In compliance with security best practices (OWASP), you should never share production credentials.noserver is designed to be the only safe place to debug live tokens because strictContent Security Policy (CSP) and network isolation enforcement ensures no data egress.