What is API Rate Limiting?
API rate limiting is a technique to control the frequency of requests that a client can make per unit time. It prevents abuse, ensures fair usage, and maintains system stability.
Key Concepts
- Requests per second (RPS): Number of allowed requests per second
- Rate limit headers: X-RateLimit-Remaining and X-RateLimit-Reset
- Throttling: Managing traffic flow rather than hard rate limits
Rate Limiting Strategies
Token Bucket
Stores excess capacity in a "bucket" to absorb traffic surges. New tokens added at fixed rate.
Leaky Bucket
Processes requests at fixed rate even during traffic bursts. Prevents sustained high volumes.
Best Practices
Client-Side Handling
- Implement retry-with-exponential-backoff
- Display rate limit warnings in UI
- Cache responses when safe
Server-Side Handling
- Use distributed rate limiting for scale
- Provide informative 429 responses
- Monitor and log abuse patterns