Authentication Patterns: JWT, Sessions, and Modern Auth

Authentication is the front door to your application. Get it wrong, and users can’t access their accounts. Get it really wrong, and attackers can access everyone’s accounts. Here’s how to navigate the modern authentication landscape.

Quick Comparison

Approach	Stateful	Scalability	Security	Complexity
Server Sessions	Yes	Limited	High	Low
JWT	No	Excellent	Medium	Medium
OAuth/OIDC	Depends	Excellent	High	High
Passwordless	No	Good	High	Medium

Server Sessions

How It Works

1. User logs in with credentials
2. Server creates session, stores in database/memory
3. Server sends session ID cookie to browser
4. Browser sends cookie with each request
5. Server looks up session, validates request

When to Use

Scenario	Good Fit?
Traditional web apps	Yes
Single server	Yes
Need to revoke instantly	Yes
Microservices	No
Mobile apps	No

Trade-offs

Pro	Con
Simple implementation	Server memory/bloat
Instant revocation	Scaling challenges
No token management	Session database required

JWT (JSON Web Tokens)

How It Works

1. User logs in with credentials
2. Server creates signed JWT with claims
3. Server sends JWT to client
4. Client stores JWT (localStorage, memory)
5. Client sends JWT in Authorization header
6. Server verifies signature, extracts claims

When to Use

Scenario	Good Fit?
Microservices	Yes
Mobile apps	Yes
Stateless services	Yes
Need instant revocation	No
High security	Add refresh tokens

Trade-offs

Pro	Con
Stateless	Cannot revoke instantly
Scales horizontally	Token size overhead
Works across services	Expiration management

OAuth 2.0 / OIDC

How It Works

1. User clicks “Login with Google”
2. App redirects to OAuth provider
3. User authenticates with provider
4. Provider redirects back with authorization code
5. App exchanges code for access token
6. App uses token to access user info

When to Use

Scenario	Good Fit?
Consumer apps	Yes
Want social login	Yes
Enterprise SSO	Yes
Simple internal tool	No

Trade-offs

Pro	Con
No password storage	Complex implementation
Social proof	Provider dependency
Better security	Redirect complexity

Modern Considerations

Refresh Tokens

| Method | Implementation | | ------ | -------------- | ------------ | | Sliding expiration | Refresh token extends on each use | | Absolute expiration | Fixed expiration time from issue | | Rotation | New refresh token on each use |

Token Storage

Storage	XSS Risk	Recommendation
HttpOnly cookie	Protected	Preferred for web
localStorage	Vulnerable	Avoid
sessionStorage	Vulnerable	Avoid
Memory	Protected	Best for mobile

Common Pitfalls

Pitfall	Impact	Prevention
JWT in localStorage	XSS vulnerability	Use HttpOnly cookies or memory
No refresh tokens	Poor UX	Implement refresh token rotation
Long JWT expiration	Security risk	Short expiration + refresh
Signing with weak secret	Token forgery	Use strong, rotated secrets
Not validating tokens	Security bypass	Always verify signature and claims

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Authentication choice impacts security, scalability, and user experience. If you need help implementing authentication for your application, book a consultation. We’ll help you choose the right approach and implement it securely.