How to Build a Rate Limiter: Design Principles and Common Pitfalls Explained

Developer Maneshwar, creator of the open-source AI code review tool git-lrc, has published a technical guide on designing production-ready rate limiters. A rate limiter controls how many requests a client can make within a set time window, protecting systems from overload and preventing any single user from consuming disproportionate resources. The guide outlines key requirements including configurable per-user limits, honest HTTP 429 rejections with informative headers, and sub-3ms latency at P95. It walks through the pitfalls of naive approaches such as in-database counters and per-server in-memory storage, both of which break down under real-world, multi-server conditions. Redis is recommended as the shared, memory-fast backbone for counters, using atomic operations and automatic key expiry to keep limits consistent across all servers.