JWT Decoder

JWT Decoder Documentation

JSON Web Tokens (JWT) are an open standard (RFC 7519) for securely transmitting information between parties as a JSON object. This tool helps you decode and inspect JWT tokens.

JWT Structure

A JWT consists of three parts separated by dots (.):

1. Header - Contains metadata about the token
2. Payload - Contains the actual data (claims)
3. Signature - Verifies the token's authenticity

Example:

xxxxx.yyyyy.zzzzz

Token Components

1. Header

• Typically contains the token type (typ) and signing algorithm (alg)
• Example:

  {
    "alg": "HS256",
    "typ": "JWT"
  }
  

2. Payload (Claims)

Common claims include:

• iss (Issuer)
• sub (Subject)
• exp (Expiration Time)
• iat (Issued At)
• aud (Audience)

3. Signature

• Created using the encoded header, payload, and a secret
• Used to verify the token hasn't been tampered with

Common Use Cases

1. Authentication

   • Single Sign-On (SSO)
   • API authentication
   • Session management

2. Information Exchange

   • Secure data transfer
   • Authorization tokens
   • User state management

3. API Security

   • Bearer tokens
   • Access control
   • Resource authorization

Security Considerations

1. Token Handling

   • Never store sensitive data in JWTs
   • Always use HTTPS for token transmission
   • Implement proper token expiration

2. Validation

   • Always verify signatures
   • Check expiration times
   • Validate issuer and audience claims

3. Best Practices

   • Use appropriate algorithms
   • Rotate secrets regularly
   • Implement token revocation when needed