Fwiw, not that it mattes a lot, I think most of that sense of quality in ZeroMQ is due to the very tasteful efforts of its main author, Martin Sustrik (https://www.250bpm.com/). Pieter Hintjens sortof stewarded the project but, I believe, didn't code all that much on it.

I did use the Xitami webserver in anger or years back in the early 2000s though, and that very much was Pieter's work! It was amazing!