Why Your .NET Rate Limiter Fails at Scale (And How to Fix It)

Get started with Redis Cloud → https://fandf.co/4bcBZAK Good news: I got Redis to give the first 1,000 of you $100 in free credits with code MILAN100, so you can follow along and try it yourself. Redis Rate Limiting with Lua: https://redis.io/tutorials/rate-limit... Want to master Clean Architecture? Go here: https://dub.sh/clean-architecture Want to master Modular Monoliths? Go here: https://dub.sh/modular-monolith Join the .NET Architects Club: https://www.skool.com/mj-tech-communi... Get the 2026 .NET Developer roadmap here → https://the-dotnet-weekly.ck.page/202... In-memory rate limiting works… until you scale beyond one server. Once your .NET API runs on multiple instances, each instance tracks rate limits independently. That means your “global” limit is no longer global. In this video, I’ll show you how to build a production-ready rate limiter in C# using Redis as the shared source of truth. We’ll start with the distributed systems problem behind rate limiting, then implement two rate limiting algorithms using Redis and StackExchange.Redis. You’ll learn: Why in-memory rate limiting breaks in distributed systems How Redis helps enforce rate limits across multiple API instances How to create a managed Redis instance with Redis Cloud How to connect a .NET app to Redis using StackExchange.Redis How to implement a fixed window rate limiter How to implement a sliding window rate limiter How to return 429 Too Many Requests How to use the Retry-After response header Why atomic operations matter for production-grade rate limiting When you should consider Lua scripting in Redis This video is sponsored by Redis Cloud. If you want to try Redis Cloud and follow along with the implementation, check the link in the pinned comment. Rate limiting looks simple at first, but once your API scales out, it quickly becomes a distributed systems problem. Redis gives us the shared storage, fast reads, TTL support, and data structures we need to solve it properly. Check out my courses: https://www.milanjovanovic.tech/courses Read my Blog here: https://www.milanjovanovic.tech/blog Join my weekly .NET newsletter: https://www.milanjovanovic.tech Chapters