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Rate Limiting Strategies for APIs: Token Bucket, Sliding Window, and Beyond

Rate limiting is one of the few backend patterns that touches every layer of the stack: it protects your API from abuse, controls costs, ensures fair usage, and prevents cascading failures. But picking the wrong algorithm or implementing it incorrectly leads to inaccurate limits, race conditions, or excessive latency. This guide compares every major rate limiting algorithm and provides production-ready implementations.

Rate Limiting Algorithms Compared

Algorithm How It Works Accuracy Memory Best For

Fixed Window Count requests in fixed time buckets (e.g., per minute) Poor (burst at boundaries) Very Low Simple limits, not recommended for production

Sliding Window Log Store timestamp of every request, count in window Perfect High When accuracy matters more than memory

Sliding…