Application Programming Interface Design and Rate Limiting Questions

Focuses on designing scalable application programming interfaces that handle high request volumes while protecting infrastructure and preserving developer experience. Topics include API surface design and versioning, idempotency and retry semantics, authentication and authorization impacts, consistency and backward compatibility, and choosing protocols and payload formats. For scaling and protection discuss rate limiting and quota strategies such as token bucket, fixed window, sliding window, leaky bucket, per API key and per user limits, and hierarchical quotas. Cover backpressure, graceful degradation, circuit breakers, throttling responses and headers that communicate limits to clients, retry guidance, and strategies to avoid thundering herd effects. Also include operational concerns: monitoring and observability for request and error rates, metrics for usage and latency, metering and billing implications for usage based pricing, developer platform experience, documentation and developer tooling, testing at scale, and trade offs between strict protection and usability.