Behind Every 429 Too Many Requests (opens in new tab)

Most developers have seen this message before: 429 Too Many Requests But what actually happens behind the scenes before a system decides to reject a request? How are requests counted? Where is that data stored? How does the system handle millions of users? And what does the architecture of a rate limiter look like? This project explores rate limiter design from the ground up, covering requirements, capacity estimation, and high-level architecture. Topics covered: Introduction What is a Rate L...