JWT Encoder

Online JWT (JSON Web Token) encoder for generating and signing JWTs with pure frontend implementation

HEADER

PAYLOAD

VERIFY SIGNATURE

ENCODED

JWT Encoder Knowledge Base

What is JWT Encoding?

JWT encoding is the process of creating a JSON Web Token, including building the Header and Payload, then signing them using a specified algorithm and secret key. The generated JWT can be used for authentication and information transmission.

JWT Generation Steps

  1. Create Header: Specify token type (JWT) and signing algorithm
  2. Create Payload: Add claims and user data
  3. Base64 Encoding: Base64URL encode the Header and Payload
  4. Create Signature: Sign the encoded data using specified algorithm and secret key
  5. Combine Token: Join the three parts with dots (.) to form the final JWT

Supported Signing Algorithms

  • HS256: HMAC SHA-256, most commonly used symmetric encryption algorithm
  • HS384: HMAC SHA-384, stronger security
  • HS512: HMAC SHA-512, highest level of security

Payload Best Practices

  • Standard Claims: Use standard fields like iss, sub, aud, exp, iat
  • Custom Claims: Add application-specific user information and permissions
  • Expiration Time: Always set reasonable exp (expiration time)
  • Data Minimization: Include only necessary information, avoid sensitive data

Security Recommendations

  • Use strong keys, at least 32 characters of random string
  • Regularly rotate keys to improve security
  • Set reasonable expiration times, usually no more than 24 hours
  • Use HTTPS to transmit JWT in production environment
  • Consider using refresh token mechanism