API Authentication and Rate Limiting

API authentication and rate limiting are essential for protecting APIs from abuse and unauthorized access.

API Authentication Methods

• API keys
• OAuth 2.0 Bearer tokens
• Mutual TLS (mTLS)
• HMAC signatures

Rate Limiting Strategies

• Fixed window rate limiting
• Sliding window rate limiting
• Token bucket algorithm
• Leaky bucket algorithm

Implementation

Use HTTP headers to communicate rate limit status:

X-RateLimit-Limit: 100
X-RateLimit-Remaining: 95
X-RateLimit-Reset: 1640000000