What is a JWT Debugger?
A JWT Debugger is an essential tool for developers working with JSON Web Tokens (JWTs). It allows you to decode, verify, and analyze JWT tokens to understand their structure, validate signatures, and troubleshoot authentication issues.
🎯 Why JWT Debuggers Are Essential
- Development: Debug authentication flows during development
- Security: Verify token integrity and detect vulnerabilities
- Troubleshooting: Identify expired or malformed tokens
- Learning: Understand JWT structure and claims
- Testing: Validate token generation and parsing
Understanding JWT Structure
JWT Token Format
A JWT consists of three parts separated by dots (.)
🔵 Header (Part 1)
Contains metadata about the token type and signing algorithm.
🟢 Payload (Part 2)
Contains the claims (user data and metadata).
🔴 Signature (Part 3)
Used to verify the token hasn't been tampered with.
How to Use Our JWT Debugger
🚀 Try Our JWT Debugger Now
Decode and verify JWT tokens instantly with our free, secure debugger tool.
🔍 Debug JWT Token →Step 1: Paste Your JWT Token
Copy and paste your JWT token into the input field. Our tool will automatically detect the format.
Step 2: View Decoded Information
See the header and payload in a readable JSON format with syntax highlighting.
Step 3: Verify Signature (Optional)
Enter your secret key to verify the token's signature and ensure authenticity.
Step 4: Analyze Results
Check expiration times, issuer information, and other important claims.
Common JWT Claims Explained
✅ Standard Claims (RFC 7519)
🔧 Custom Claims
You can add custom claims to store additional user information:
JWT Security Best Practices
⚠️ Common JWT Security Mistakes
- Weak Secrets: Using predictable or short secret keys
- Long Expiration: Setting tokens to expire too far in the future
- Sensitive Data: Storing passwords or sensitive info in payload
- No Validation: Not verifying token signature on server
- Insecure Storage: Storing tokens in localStorage without encryption
✅ JWT Security Best Practices
- Strong Secrets: Use cryptographically secure random keys
- Short Expiration: Set reasonable expiration times (15-60 minutes)
- Refresh Tokens: Implement refresh token rotation
- HTTPS Only: Always transmit tokens over secure connections
- Token Validation: Verify signature and claims on every request
- Secure Storage: Use httpOnly cookies or secure storage mechanisms
JWT vs Other Authentication Methods
| Method | Pros | Cons |
|---|---|---|
| JWT | Stateless, scalable, self-contained | Cannot be revoked easily, larger size |
| Session Cookies | Can be revoked, smaller size | Requires server storage, not stateless |
| OAuth 2.0 | Industry standard, secure | Complex implementation, multiple requests |
Frequently Asked Questions
Can JWT tokens be revoked?
JWTs are stateless by design, so they cannot be revoked once issued. Use short expiration times and refresh tokens for better security.
How long should JWT tokens be valid?
Access tokens should be short-lived (15-60 minutes), while refresh tokens can be longer (7-30 days) depending on your security requirements.
Is it safe to decode JWT tokens on the client?
Decoding is safe since JWTs are base64 encoded, but never trust client-side validation. Always verify signatures on the server.
What's the difference between JWT and JWE?
JWT (JSON Web Token) is signed but not encrypted. JWE (JSON Web Encryption) encrypts the payload for additional security.
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