Rate Limiting

Table of Contents Introduction Why Rate Limiting Matters in Microservices Fundamental Rate‑Limiting Algorithms 3.1 Fixed Window Counter 3.2 Sliding Window Log 3.3 Sliding Window Counter 3.4 Token Bucket 3.5 Leaky Bucket Challenges of Distributed Environments Designing a Distributed Rate Limiter 5.1 Choosing the Right Data Store 5.2 Consistency Models and Trade‑offs 5.3 Sharding & Partitioning Strategies Implementation Walk‑throughs 6.1 Redis‑Based Token Bucket (Go) 6.2 Apache Cassandra Sliding Window Counter (Java) 6.3 gRPC Interceptor for Centralised Enforcement (Node.js) Testing, Metrics, and Observability Best Practices & Anti‑Patterns Case Study: Scaling Rate Limiting for a Global E‑Commerce Platform Conclusion Resources Introduction Modern applications are increasingly built as collections of loosely coupled microservices that communicate over HTTP/REST, gRPC, or message queues. While this architecture brings agility and scalability, it also introduces new operational challenges—one of the most pervasive being rate limiting. Rate limiting protects downstream services from overload, enforces fair usage policies, and helps maintain a predictable quality of service (QoS) for end‑users. ...

Introduction In modern web services, protecting APIs from abuse, ensuring fair resource allocation, and maintaining a predictable quality‑of‑service are non‑negotiable requirements. Rate limiting—the practice of restricting how many requests a client can make in a given time window—addresses these concerns. While a simple in‑process limiter works for monolithic applications, today’s micro‑service ecosystems demand a distributed solution that works across multiple instances, data centers, and even cloud regions. This article walks you through the complete design and implementation of a distributed rate limiter built on Redis using the Token Bucket algorithm. We’ll cover the theory behind token buckets, why Redis is a natural fit, practical implementation details, edge‑case handling, scaling strategies, and real‑world patterns you can adopt immediately. ...