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JWT Decoder Documentation
🔐What is JWT?
JSON Web Token (JWT) is an open standard (RFC 7519) that defines a compact and self-contained way for securely transmitting information between parties as a JSON object. JWTs can be signed using a secret (HMAC algorithm) or a public/private key pair (RSA or ECDSA).
A JWT consists of three parts:
- Header - Contains metadata about the token (type and signing algorithm)
- Payload - Contains the claims (statements about an entity)
- Signature - Ensures the token hasn't been altered
🔒Supported Algorithms
HMAC Algorithms:
- HS256 - HMAC using SHA-256 hash algorithm
Best for most general-purpose applications
- HS384 - HMAC using SHA-384 hash algorithm
Provides additional security with longer hash length
- HS512 - HMAC using SHA-512 hash algorithm
Highest security level for HMAC, but requires more processing
RSA Algorithms:
- RS256 - RSA Signature with SHA-256
Most commonly used RSA algorithm
- RS384 - RSA Signature with SHA-384
Enhanced security for RSA signatures
- RS512 - RSA Signature with SHA-512
Maximum security for RSA signatures
📝Common JWT Claims
Registered claims (standardized):
- iss (Issuer) - Who issued the token
- sub (Subject) - Who the token refers to
- aud (Audience) - Who the token is intended for
- exp (Expiration Time) - When the token expires
- nbf (Not Before) - When the token becomes valid
- iat (Issued At) - When the token was issued
- jti (JWT ID) - Unique identifier for the token
⚡Features & Capabilities
- Real-time JWT decoding and validation
- Detailed header and payload visualization
- Support for multiple signature verification algorithms
- Automatic JSON pretty printing
- Base64URL encoding/decoding
- Error handling and validation feedback
- Support for both symmetric and asymmetric keys
🛡️Security Best Practices
- Signature Verification
Always verify JWT signatures in production environments
- Key Management
Use strong, unique keys and implement proper key rotation policies
- Payload Security
Never store sensitive information in JWT payloads as they are base64 encoded
- Token Expiration
Always include and verify expiration times (exp claim)
- Algorithm Selection
Choose appropriate algorithms based on security requirements
🔍Common Use Cases
- Authentication and Authorization
- Single Sign-On (SSO)
- API Authentication
- Information Exchange
- Stateless Sessions
- Mobile App Authentication
- Cross-Origin Resource Sharing