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JWT vs. Session Tokens

A practical security comparison of JWTs and server-side session tokens for authentication.

A

JWT (JSON Web Tokens)

Pros
  • ✓ Stateless — no database lookup per request
  • ✓ Works across microservices and domains
  • ✓ Self-contained claims
  • ✓ Good for APIs and mobile apps
Cons
  • ✗ Cannot be invalidated without a denylist (stateful again)
  • ✗ Larger than a session ID
  • ✗ If secret is leaked, all tokens are compromised
  • ✗ Common security mistakes: alg:none attack, weak secrets
BEST FOR
Microservices where stateless auth is needed, third-party API access, mobile apps, short-lived tokens
B

Session Tokens (server-side)

Pros
  • ✓ Can be invalidated instantly (logout works correctly)
  • ✓ Smaller token (just an ID)
  • ✓ All session data stays on server
  • ✓ More secure by default
Cons
  • ✗ Requires server-side storage (Redis, database)
  • ✗ Harder to scale horizontally without sticky sessions or shared session store
  • ✗ Not suitable for third-party API access
BEST FOR
Traditional web apps, situations where immediate revocation is needed (admin logout, password reset), apps with strict security requirements
Verdict

For most web apps with a single backend, session tokens are simpler and more secure. Use JWTs for microservices, mobile apps, or when stateless auth is architecturally required — but use short expiry times and a token refresh strategy.

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