Mercurial and Mirrors…
Mercurial is a distributed revision-control tool for software developers. It is supported on Microsoft Windows and Unix-like systems, such as FreeBSD, macOS and Linux.
In software development, distributed version control (also known as distributed revision control) is a form of version control where the complete codebase - including its full history - is mirrored on every developer's computer.[1] This allows branching and merging to be managed automatically, increases speeds of most operations (except for pushing and pulling), improves the ability to work offline, and does not rely on a single location for backups.
https://en.wikipedia.org/wiki/Mercurial