[rochoa]

There is also https://github.com/kevinlawler/kerf

> Kerf2 is designed for full concurrency. It also adds transparent type promotion, a C++ instead of C basis, and more.

Which goes unlicensed right now and was created just a bit before the license change in Kerf1. I wonder if Kerf1 will get any more attention or the focus is now at Kerf2.