TsutomuSenkawa

If you're in this space you've heard all about tools like Anubis and Haproxy-protection and the various Lua engines out there, but this is the first PoW program built as a true network stack primitive. It's a composable drop-in microservice designed to work with any server that can speak HTTP and make a hash, and gives it powerful proof-of-work defense capability. In 1 megabyte. In development for over two years, and running on real websites since 2025. It went public a couple weeks ago.

Varnish gurus should especially love it.