Elizabeth Mosley

Choosing the right authentication strategy affects security, scalability, and user experience. JWT and session-based authentication each solve different problems with distinct trade-offs.

Session-Based Authentication

Traditional approach storing session data server-side:

Flow:

1. User logs in with credentials
2. Server creates session, stores in database/memory
3. Server sends session ID via cookie
4. Client includes cookie in subsequent requests
5. Server validates session ID against storage

// Laravel example
Route::post('/login', function (Request $request) {
    if (Auth::attempt($request->only('email', 'password'))) {
        $request->session()->regenerate();
        return response()->json(['message' => 'Logged in']);
    }
    return response()->json(['error' => 'Invalid'], 401);
});

Advantages:

• Easy to invalidate (logout)
• Smaller request size
• Server controls all sessions
• Familiar pattern

Disadvantages:

• Requires server-side storage
• Harder to scale horizontally
• Not ideal for microservices
• CSRF vulnerabilities

JWT (JSON Web Tokens)

Stateless authentication using signed tokens:

Flow:

1. User logs in
2. Server generates JWT containing user data
3. Client stores JWT (localStorage/cookie)
4. Client includes JWT in Authorization header
5. Server validates JWT signature

// Node.js example
const jwt = require('jsonwebtoken');

app.post('/login', (req, res) => {
  // Validate credentials
  const token = jwt.sign(
    { userId: user.id, email: user.email },
    process.env.JWT_SECRET,
    { expiresIn: '24h' }
  );
  res.json({ token });
});

// Middleware to verify
function authenticateToken(req, res, next) {
  const token = req.headers['authorization']?.split(' ')[1];
  if (!token) return res.sendStatus(401);
  
  jwt.verify(token, process.env.JWT_SECRET, (err, user) => {
    if (err) return res.sendStatus(403);
    req.user = user;
    next();
  });
}

Advantages:

• Stateless (no server storage)
• Scales horizontally
• Perfect for microservices
• Mobile-friendly

Disadvantages:

• Difficult to revoke before expiration
• Larger request size
• Token storage security concerns
• Need refresh token strategy

Security Considerations

Sessions:

• Use HTTPS only
• Set HttpOnly, Secure, SameSite flags on cookies
• Implement CSRF tokens
• Regenerate session IDs after login

JWT:

• Store securely (HttpOnly cookies preferred over localStorage)
• Use short expiration times
• Implement refresh tokens
• Never store sensitive data in payload
• Validate on every request

Hybrid Approach

Many applications use both:

• Sessions for web applications
• JWT for mobile apps and APIs
• Refresh tokens for extending JWT life without re-authentication

Making the Choice

Choose Sessions when:

• Building traditional web applications
• Need immediate logout capability
• Operating in monolithic architecture
• Fine-grained control over sessions required

Choose JWT when:

• Building APIs for multiple clients
• Implementing microservices
• Mobile apps are primary clients
• Horizontal scaling is priority

Neither solution is universally superior—context determines the appropriate choice. Many modern applications successfully implement hybrid approaches, using the right tool for each use case.

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