Hyperscaling Have I Been Pwned with Cloudflare Workers and Caching
Published on: 2025-08-14 09:51:24
I've spent more than a decade now writing about how to make Have I Been Pwned (HIBP) fast. Really fast. Fast to the extent that sometimes, it was even too fast:
The response from each search was coming back so quickly that the user wasn’t sure if it was legitimately checking subsequent addresses they entered or if there was a glitch.
Over the years, the service has evolved to use emerging new techniques to not just make things fast, but make them scale more under load, increase availability and sometimes, even drive down cost. For example, 8 years ago now I started rolling the most important services to Azure Functions, "serverless" code that was no longer bound by logical machines and would just scale out to whatever volume of requests was thrown at it. And just last year, I turned on Cloudflare cache reserve to ensure that all cachable objects remained cached, even under conditions where they previously would have been evicted.
And now, the pièce de résistance, the coolest perform
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