Best Practices for JWT Authentication

JSON Web Tokens (JWT) are the standard for securing modern web applications and APIs. However, if implemented incorrectly, they can open up severe security vulnerabilities like Cross-Site Scripting (XSS) and Cross-Site Request Forgery (CSRF).

Where to Store Your Tokens

The most common debate in JWT authentication is where to store the token on the client side. There are two main options:

• Local Storage: Very easy to implement, but vulnerable to XSS attacks. If a hacker runs JavaScript on your site, they can steal the token.
• HttpOnly Cookies: More secure against XSS, but requires CSRF protection.

The Ideal Approach: HttpOnly Cookies

For maximum security, always store your JWTs in an HttpOnly cookie. This prevents any JavaScript on the page from reading the token. When you make an API request, the browser will automatically include the cookie.

Keep Tokens Short-Lived

Because JWTs are stateless (meaning they cannot easily be revoked without complex database blacklists), you should set the expiration time (exp) to be very short, such as 15 minutes. Pair this with a longer-lived Refresh Token stored securely.

Conclusion

Authentication is hard. When building platforms like AI ToolYes, leveraging robust backend frameworks or services like Supabase can save you from reinventing the wheel and making critical security mistakes.