How Cloudflare built rate limiting that scaled to millions of domains

Cloudflare is one of the cloud companies that continues to keep on impressing me.

I’ve built a few rate limiters in my career but if someone asked me how to build a rate limiter at internet scale, I would have to think hard.

Their solution seems simple and intuitive once you read about it, but I bet they’ve spent weeks thinking about different designs and their tradeoffs.

That’s what I love about Engineering. Some problems make you and your team think hard for weeks. Designing many solutions on paper (or prototyping them) and creatively destroying them until you get one that has a good balance of tradeoffs.

What was their secret? Yichun Zhang @agentzh

Apparently he founded his own company now.