API Security Best Practices
API security guide. Authentication methods, best practices, common vulnerabilities. Secure your API endpoints.
Authentication Methods
API Key: Simple, identify applications
Pros: Easy, fast
Cons: No user context, can leak
OAuth 2.0: User authorization, third-party
Pros: Secure, user context
Cons: Complex, redirect flow
JWT: Self-contained tokens
Pros: Stateless, scalable
Cons: Token size, expiry handling
Basic Auth: Username/password header
Pros: Simple
Cons: Not secure without TLS
Session Cookie: Server-side session
Pros: Simple logout
Cons: Server storage needed
Security Best Practices
Always use HTTPS/TLS
Never store secrets in code
Use environment variables
Implement rate limiting
Validate all input
Sanitize output
Use CORS properly
Log authentication attempts
Implement token rotation
Set appropriate expiry
Use short-lived tokens
Implement scopes/permissions
Common Vulnerabilities & Fixes
SQL Injection: Use parameterized queries, ORM
Broken Authentication: Strong passwords, MFA, secure sessions
Sensitive Data Exposure: Encrypt data, HTTPS, minimize storage
Rate Limiting Missing: Implement throttling per key/user
Broken Access Control: Check permissions on every request
Security Misconfiguration: Hardened defaults, error handling
Security Headers
Authorization: Bearer token or API key
X-API-Key: Custom API key header
X-Request-ID: Unique request tracking
X-RateLimit-Limit: Rate limit information
X-RateLimit-Remaining: Remaining requests
Rate Limiting Strategy
Implement rate limiting: by IP address (simple), by API key (per application), by user ID (per user). Typical limits: 100 requests/minute, 1000/hour. Response: 429 Too Many Requests, Retry-After header. Use: Redis for counters, sliding window algorithm. Protect against: DDoS, abuse, brute force.
JWT Security Tips
JWT best practices: short expiry (15-30 min), use refresh tokens, strong secret key, validate signature, check expiry, verify issuer, implement scopes, don't store sensitive data in payload, use HTTPS, rotate signing keys periodically. Never accept unsigned tokens.