JWT Debugger
NewComprehensive JWT debugging tool that decodes, validates, and security-analyzes JSON Web Tokens. Displays the decoded header, payload, and signature in a clean formatted view. Checks for security issues: algorithm set to "none", weak algorithms, expired tokens, overly broad scopes, and sensitive data in the payload. Supports HMAC signature verification with a provided secret. A must-have for developers working with authentication systems.
JWT Debugger
Visual JWT debugger — decode header, payload and inspect claims. Color-coded like jwt.io.
How to Use JWT Debugger
- 1Paste a JWT token (three parts separated by dots)
- 2View decoded header and payload
- 3Optionally provide the secret to verify signature
- 4Review security warnings and findings
Your Privacy is Protected
JWT Debugger runs entirely in your browser. Your files and data are never uploaded to any server, never stored, and never shared. Everything happens locally on your device using secure browser APIs.
Frequently Asked Questions
What security issues can JWT debugger find?
It can detect: algorithm set to "none" (critical), expired tokens, missing expiry claims, sensitive PII in payload, overly long expiry times, and weak algorithms like HS1.
Why Use This Tool?
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