PureDarwin – a community project to make Darwin more usable (some people think of it as the informal successor to OpenDarwin).
Darwin is the Open Source operating system from Apple that forms the basis for macOS.
The goal of the PureDarwin project is to make Darwin more usable for open source enthusiasts and developers by providing documentation and by enabling them to retrieve, understand, modify, build, and distribute Darwin.
UseD components are specifically released by Apple for use with Darwin, as well as other Open Source components (collectively called “upstream code”). Specifically, it means that we do not use any components from Mac OS X. It also means that we try to stay as close as possible to the “outside world” as in Mac OS X (e.g., regarding the choice of compilers, options, etc.). It does not mean, however, that we do not modify and add to the upstream code, to the extent that the respective licenses allow.