Node.js API Rate Limiting in Production: From express-rate-limit to Redis-Backed Distributed Throttling

Node.js API Rate Limiting in Production: From express-rate-limit to Redis-Backed Distributed Throttling Rate limiting is one of those production concerns engineers defer until something breaks. Then at 2 AM, a bot hammers your /auth/login endpoint 50,000 times in three minutes and your database goes down. This guide will make sure that never happens to you. We'll cover everything: algorithm theory, express-rate-limit configuration, Redis-backed distributed limiting for multi-instance deployments, per-route policies, API key tiers, and RFC-compliant 429 responses — the ones clients can actually act on. Why Rate Limiting Is Non-Negotiable Before diving in, understand what you're protecting against: Credential stuffing: Automated login attempts using leaked passwords from other breaches DDoS amplification: Small requests that trigger expensive downstream work (database queries, external API calls) Scraping abuse: Bots consuming your data faster than paying customers Cost explosions: AI in