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Advanced 20 min readModule: Module 7: API Gateway & Rate Limiting Algorithms

API Gateways & Rate Limiting Algorithms

Protect downstream microservices using Token Bucket, Sliding Window Rate Limiters, and API Gateways.

What You Will Learn in This Lesson

  • The 4 Rate Limiting Algorithms: Token Bucket, Leaky Bucket, Fixed Window, Sliding Window
  • Distributed rate limiting with Redis sliding logs and Lua scripts
  • API Gateway responsibilities: Routing, Auth, Rate Limiting, SSL Termination

Introduction & Core Concept

A rate limiter controls the rate of traffic sent by a client or service. In the HTTP world, a rate limiter limits the number of client requests allowed within a specified time window.
WHY DOES THIS MATTER IN THE REAL WORLD?

Rate limiting defends systems against Denial of Service (DoS) attacks, brute force attempts, and abusive scraping.

Token Bucket Algorithm Concept

javascript
javascript
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// Token bucket refills at 10 tokens/sec up to capacity of 50 tokens
// Each API request consumes 1 token; if bucket is empty, return HTTP 429 Too Many Requests
console.log("Token Bucket allows short bursts while enforcing steady long-term limits.");

Line-by-Line Technical Breakdown

1Return HTTP 429 Too Many Requests with Retry-After headers when limits are exceeded.

Try It Yourself (Interactive Editor)

Modify the code in real-time and click Run to test live browser output and console logs.

Intelligent Code Runner & Live Sandbox[JAVASCRIPT]
JAVASCRIPT SOURCE EDITOR
Interactive Live Code

Industry Best Practices & Professional Standards

  • Use Redis Lua scripts for atomic distributed rate limit token increments.

Lesson Summary & Core Takeaways

  • API Gateways and rate limiting protect microservices from overload and abuse.