Introduction
JSON Web Tokens (JWT) are widely used for authentication and information exchange in web applications. Our JWT Decoder lets you inspect the contents of any JWT, view the header and payload, and verify the signature. Debug your tokens and understand what data they contain.
The tool runs entirely in your browser with no server-side processing. Your data never leaves your device, ensuring complete privacy and security. No registration required - just open and use.
Key Features
- 1 Instant JWT decoding and display
- 2 View header, payload, and signature separately
- 3 Color-coded JSON syntax highlighting
- 4 Validate JWT signature and structure
- 5 Copy decoded JSON to clipboard
- 6 Support for both compact and pretty JSON
- 7 Error detection for malformed tokens
- 8 Explanation of each JWT component
- 9 Works with access tokens, ID tokens, and custom JWTs
- 10 Privacy: all decoding in your browser
- 11 No tokens stored or transmitted
- 12 Mobile-friendly responsive design
How to Use
- 1 Paste your JWT token in the input field
- 2 View decoded header, payload, and signature instantly
- 3 Inspect claims in the payload: iss, exp, sub, etc.
- 4 Validate token signature and structure
- 5 Copy decoded JSON or individual claims to clipboard
Why Choose This Tool
Instant Decoding
Paste any JWT and see its contents immediately. No need to understand base64 encoding.
Color-Coded JSON
Decoded JSON is syntax-highlighted for readability. Easy to scan for specific claims.
Component Separation
Header, payload, and signature are shown separately. Understand each part's role clearly.
Error Detection
Malformed tokens are flagged with helpful error messages. Debug authentication issues faster.
Explanation Tooltips
Hover over any claim (exp, nbf, aud) to see what it means. Learn JWT as you debug.
Complete Privacy
JWTs may contain sensitive user data. All decoding stays in your browser - tokens are never sent anywhere.
Common Use Cases
Debug authentication issues in web applications
Inspect access tokens and ID tokens from OAuth providers
Verify token claims before accepting them in your code
Understand what data your JWT contains
Test token expiration and renewal logic
Decode API tokens for debugging requests
Learn JWT structure and standard claims
Validate token signature for security testing