JWT Parser
Parse, decode, and validate JSON Web Tokens (JWT) with header, payload, and signature analysis
JWT Parser
Parse, decode, and validate JSON Web Tokens (JWT) with header, payload, and signature analysis
JWT Token Parser
Example JWT Tokens
🔒 Symmetric Algorithms
🔐 Asymmetric Algorithms
About JWT Token Parsing
JSON Web Tokens (JWT) are compact, URL-safe tokens that represent claims between parties. They consist of three Base64-encoded parts separated by dots: header, payload, and signature. JWT parsing allows developers to examine token contents, validate structure, verify expiration, and debug authentication issues in web applications and APIs.
- Decode JWT headers to see algorithm and token type
- Extract payload claims including user data and permissions
- Analyze token expiration and issued dates
- Validate token structure and format
- Debug authentication and authorization issues
JWT Token Structure
Token Components
- Header: Algorithm and token type
- Payload: Claims and user data
- Signature: Verification hash
- Format: header.payload.signature
- Encoding: Base64URL for each part
- Separator: Dot (.) between components
Common Claims
- iss: Issuer (who created the token)
- sub: Subject (user identifier)
- aud: Audience (intended recipient)
- exp: Expiration time (Unix timestamp)
- iat: Issued at time
- nbf: Not before time
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Frequently Asked Questions
Is it safe to decode JWTs on client-side tools?
JWT parsing only decodes the Base64-encoded content and doesn't require the secret key. The header and payload are not encrypted, only signed. However, avoid pasting sensitive tokens into online tools. Use this parser for development and debugging, not production tokens with sensitive data.
What's the difference between decoding and verifying a JWT?
Decoding reads the token content without validation. Verification checks the signature using the secret key to ensure the token hasn't been tampered with. Our parser decodes tokens to show content but cannot verify signatures without the secret key, which should never be shared.
How can I tell if a JWT is expired?
Check the "exp" claim in the payload, which contains a Unix timestamp. If the current time is greater than this timestamp, the token is expired. Our parser automatically shows expiration status and converts timestamps to readable dates for easy verification.
What algorithms are commonly used for JWT signing?
Common algorithms include HS256 (HMAC SHA-256) for symmetric signing, RS256 (RSA SHA-256) for asymmetric signing, and ES256 (ECDSA SHA-256). The algorithm is specified in the token header. HS256 uses shared secrets while RS256 uses public/private key pairs.
JWT Token Examples
Sample JWT Analysis:
Sponsored Content
JWT Signing Algorithms
Symmetric Algorithms:
Asymmetric Algorithms:
JWT Security Best Practices
Security Guidelines:
Common Vulnerabilities:
Standard JWT Claims
Reserved Claims:
Custom Claims Examples:
Common Use Cases
- Debugging authentication issues
- Analyzing token expiration problems
- Inspecting user claims and permissions
- Validating token structure and format
- API integration testing
- Understanding OAuth token contents
- Troubleshooting SSO implementations
- Learning JWT structure and claims
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