[starseeker]

I'm quite intrigued by the libfossil project (http://fossil.wanderinghorse.net/repos/libfossil) which attempts to make the core fossil VCS abilities available as a library. To the best of my understanding this is and will remain a "spin-off" project of the main fossil project, but it looks like as of August 2016 there is still active work on it.

The combination of the BSD license and a self-contained C library in the style of sqlite that offers VCS capabilities app developers could build into their applications is extremely enticing. libgit2 (https://libgit2.github.com/) may have matured enough to be viable for that use case if one is comfortable with GPLv2 plus linking exception, but the sqlite-style include one header, build one C file and you're done integration is really really nice.