JWT Decoder
Decode and analyze JSON Web Tokens (JWT). View header, payload, and signature information with validation and security analysis.
JWT Token Input
Paste a JWT token to see decoded information
Quick Examples
JWT Security & Best Practices
✓ Security Best Practices
- • Use strong signing algorithms (RS256, ES256)
- • Set appropriate expiration times
- • Validate all claims on the server
- • Use HTTPS for token transmission
- • Store tokens securely (httpOnly cookies)
- • Implement proper token refresh
✗ Security Risks
- • Never store sensitive data in payload
- • Don't rely on client-side validation only
- • Avoid using 'none' algorithm
- • Don't expose tokens in URLs
- • Don't use weak signing secrets
- • Avoid long expiration times
Standard Claims
- • iss: Issuer
- • sub: Subject
- • aud: Audience
- • exp: Expiration time
- • iat: Issued at
- • nbf: Not before
- • jti: JWT ID
Understanding JSON Web Tokens
What is a JWT?
JSON Web Token (JWT) is an open standard for securely transmitting information between parties as a JSON object. JWTs are commonly used for authentication and authorization in web applications and APIs.
A JWT consists of three parts separated by dots: Header.Payload.Signature, each encoded in Base64URL format.
JWT Structure
Header: Contains metadata about the token, including the signing algorithm.
Payload: Contains the claims (statements about an entity and additional metadata).
Signature: Used to verify the token hasn't been tampered with.
JWT Decoder Features
Token Parsing
Automatically decode and parse JWT tokens into readable header, payload, and signature components.
Claims Analysis
View and analyze standard and custom claims including expiration, issuer, audience, and more.
Security Validation
Check token expiration, validate structure, and identify potential security issues.
Security Notice
This JWT decoder runs entirely in your browser and does not transmit any token data to external servers. However, never decode production JWTs containing sensitive information on shared or untrusted devices. This tool is for development, debugging, and educational purposes only.