JWT (JSON Web Token) and Session authentication are two common authentication mechanisms with the following key differences:
1. Storage Location
- JWT: Stored on the client side (typically in LocalStorage or Cookie), passed via HTTP Header with each request
- Session: Stored on the server side (memory, Redis, database, etc.), client only stores Session ID (usually in Cookie)
2. Stateless vs Stateful
- JWT: Stateless, server doesn't need to store session information, each request contains all necessary information
- Session: Stateful, server needs to maintain session storage, consuming server memory
3. Scalability
- JWT: Easy to scale horizontally, any server can verify JWT without sharing session state
- Session: Poorer scalability, multiple servers need to share session storage (e.g., Redis cluster)
4. Security
- JWT:
- Pros: Can set expiration time, use HTTPS for transmission
- Cons: Cannot be actively revoked once issued, valid until expiration if leaked
- Session:
- Pros: Sessions can be actively destroyed, higher security
- Cons: Session ID can be hijacked (CSRF attack)
5. Data Size
- JWT: Contains user information, larger token (typically 1-2KB)
- Session: Only stores Session ID, smaller (tens of bytes)
6. Cross-Domain Support
- JWT: Naturally supports cross-domain, suitable for mobile apps and distributed systems
- Session: Needs to handle cross-domain Cookie issues, more complex configuration
7. Performance
- JWT: Requires signature verification with each request, higher computational overhead
- Session: Only needs to look up Session ID, better performance
Use Cases
Use JWT when:
- Distributed systems and microservices architecture
- Mobile applications and Single Page Applications (SPA)
- APIs requiring cross-domain access
- Third-party authorization (OAuth2.0)
Use Session when:
- Traditional web applications
- Scenarios requiring real-time permission revocation
- Systems with extremely high security requirements
- Applications with relatively smaller user base
Best Practices
- Can combine both: JWT for API authentication, Session for admin panels
- Always use HTTPS with JWT
- Set reasonable expiration times
- Sensitive operations require secondary verification