Question 1

What's the main difference between JWT and sessions?

Accepted Answer

JWT is stateless — the token contains all user data and is verified by signature. Sessions are stateful — the server stores session data and the client only holds a session ID. JWT scales better horizontally but sessions are easier to revoke.

Question 2

Is JWT more secure than session authentication?

Accepted Answer

Neither is inherently more secure. JWTs are vulnerable to token theft if stored in localStorage without proper XSS protection. Sessions using httpOnly cookies offer better CSRF protection but require server-side storage. The right choice depends on your threat model.

Question 3

Where should I store JWT tokens?

Accepted Answer

For web apps, store JWTs in httpOnly secure cookies instead of localStorage to prevent XSS attacks. For mobile apps, use secure device storage. Never store sensitive JWTs in sessionStorage or localStorage without additional protection.

Question 4

Can I revoke a JWT before it expires?

Accepted Answer

JWTs are inherently non-revocable since they're stateless. To support revocation, you need a blocklist or database check on each request, which defeats the stateless advantage. This is a key reason to choose sessions when revocation is critical.

Aspect	JWT (Token-based)	Session (Cookie-based)
State	Stateless — token contains all data	Stateful — session stored on server
Scalability	Excellent — no server-side storage needed	Requires shared session store (Redis, DB)
Revocation	Difficult — must maintain a blocklist	Easy — delete session from store
Storage	localStorage, cookies, or mobile storage	httpOnly cookie (session ID only)
CSRF Protection	Not vulnerable if stored in auth header	Requires CSRF tokens or SameSite cookies
Cross-domain	Works across domains and microservices	Difficult — cookies are domain-specific

JWT vs Session Authentication

Comparison at a Glance

When to Choose Each Approach

Choose JWT for APIs

Choose Sessions for Web Apps

Choose JWT for SSO

Choose Sessions for Banking/Finance