Modern Authentication Patterns

Authentication is the most critical part of any backend system. Rolling your own crypto is a notoriously bad idea, but understanding how tokens flow through your app is essential.

• JWTs vs Sessions: JSON Web Tokens (JWTs) are excellent for stateless APIs, but they are incredibly difficult to invalidate before they expire. Server-side sessions offer better control but require database lookups on every request.
• Storage Security: Never store access tokens in localStorage. They are highly vulnerable to Cross-Site Scripting (XSS) attacks. Always use HttpOnly, Secure cookies to store sensitive tokens so they cannot be read by frontend JavaScript.
• OAuth 2.0: Delegating auth to providers like Google or GitHub not only reduces the risk of managing passwords but drastically improves user conversion rates by removing friction.