JWT Decoder
Decode JWT tokens instantly. View header, payload, and signature information with validation checks.
JWT Structure
- • Header: Algorithm and token type
- • Payload: Claims and user data
- • Signature: Verification signature
- • Format: Base64Url encoded parts
- • Separator: Parts separated by dots
Common Claims
- • sub: Subject (user ID)
- • iss: Issuer (who created)
- • aud: Audience (who can use)
- • exp: Expiration time
- • iat: Issued at time
- • nbf: Not before time
Security Notes
- • Never store sensitive data in JWT payload
- • Always validate signature on server-side
- • Use short expiration times for security
- • Implement token refresh mechanism
- • Use strong algorithms like RS256
JWT decoding is essential for debugging authentication, API development, and security analysis. Developers use it for debugging token issues and understanding API authentication. Security professionals use it for analyzing token security and validating claims. QA engineers use it for testing authentication flows. System administrators use it for troubleshooting access issues. Our decoder provides comprehensive JWT analysis with claim validation and security checks, making it perfect for development, security, testing, and administration.
Algorithm Selection: Use strong algorithms like RS256 over HS256. Secret Management: Keep signing keys secure and rotate regularly. Token Expiration: Set short expiration times for security. Claim Validation: Always validate all claims on server-side. Token Refresh: Implement refresh token mechanism. These practices ensure secure JWT implementation.
Expired Tokens: Check exp claim against current time. Invalid Signature: Token tampered or wrong secret. Malformed Token: Incorrect format or encoding. Future Tokens: nbf claim not yet reached. Invalid Claims: Missing or incorrect required claims. Understanding these issues helps debug JWT problems.
Authentication: User login and session management. API Security: Securing API endpoints and requests. Single Sign-On: Cross-application authentication. Authorization: Role-based access control. Information Exchange: Secure data transfer between services. Each use case requires specific JWT configuration and validation.
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