JWT Security Best Practices

Essential guidelines for implementing secure JWT authentication

JSON Web Tokens (JWT) are a powerful tool for authentication and authorization, but they must be implemented correctly to ensure security. This guide covers essential best practices for JWT implementation in production environments.

Secure Key Generation

Use cryptographically secure random number generators for key generation
Implement minimum key length of 64 characters for production
Choose HS512 (HMAC with SHA-512) for maximum security
Store keys securely in environment variables, never in code
Implement regular key rotation schedules

Token Structure and Claims

Include expiration (exp) and issued at (iat) claims
Set appropriate token expiration times (max 24 hours recommended)
Use audience (aud) and issuer (iss) claims for validation
Minimize sensitive data in payload
Implement JTI (JWT ID) for token revocation capability

Security Pitfalls to Avoid

Never store tokens in localStorage due to XSS vulnerability

Avoid using weak algorithms like HS256 for signing

Don't store sensitive user data in token payload

Never share signing keys across different services

Don't use predictable values for keys

Avoid long-lived tokens without refresh mechanism

Implementation Guidelines

Implement secure token transmission over HTTPS only
Use httpOnly cookies for token storage
Implement proper CORS policies
Add rate limiting for token generation endpoints
Implement token refresh mechanism
Monitor and log JWT-related security events

Additional Resources

For more detailed information about JWT security, consult these authoritative resources:

OWASP JWT Security Cheat Sheet
RFC 7519 - JWT Standard
Auth0 JWT Handbook