JWT Authentication in FastAPI: Best Practices

Understanding JWT Authentication

JSON Web Tokens (JWT) provide a stateless authentication mechanism perfect for modern APIs. Let's implement secure JWT authentication in FastAPI.

Setting Up Dependencies

pip install python-jose[cryptography] passlib[bcrypt] python-multipart

Creating JWT Tokens

Implement token creation with proper expiration:

from jose import jwt
from datetime import datetime, timedelta

def create_access_token(data: dict):
    to_encode = data.copy()
    expire = datetime.utcnow() + timedelta(minutes=30)
    to_encode.update({"exp": expire})
    return jwt.encode(to_encode, SECRET_KEY, algorithm="HS256")

Refresh Token Strategy

Implement refresh tokens for better security:

• Short-lived access tokens (15-30 minutes)
• Long-lived refresh tokens (7-30 days)
• Token rotation on refresh
• Secure storage in httpOnly cookies

Security Best Practices

• Use strong secret keys (32+ characters)
• Implement token blacklisting for logout
• Add rate limiting to prevent brute force
• Use HTTPS in production
• Validate token signatures properly