Building a Production-Ready Rate Limiter in Node.js

Building a Production-Ready Rate Limiter in Node.js Rate limiting is one of those things developers ignore until they get hit by a botnet, a runaway script, or a competitor scraping their API. By then, it's too late — your server is melting, your database is overwhelmed, and legitimate users are getting errors. In this guide, we'll build a production-ready rate limiter from scratch in Node.js. We'll implement the token bucket algorithm, integrate Redis for distributed rate limiting across multiple servers, add a sliding window counter for precision, and package everything as a reusable Express middleware. This isn't a "just install express-rate-limit" tutorial. We're going deep — understanding the algorithms, their tradeoffs, and how to make rate limiting work reliably at scale. Why Rate Limiting Matters Before we write code, let's be clear about what we're protecting against: DDoS mitigation — Limit how fast any single IP can send requests API abuse — Prevent one customer from consumi