FooSync is a filesystem directory synchronizer. It's specifically designed to support a repository shared by multiple computers. This repository can be used as a backup and/or to keep multiple computers synchronized.
It's written in C#/.NET, and designed as a console app, GUI app, and network service.
The console app and network service are designed to work in Linux with the Mono runtime, as well as Windows with the .NET runtime (version 4.0 or higher). The GUI version only works under Windows, as WPF is not supported by Mono.
"Windows support" means any version capable of running .NET 4.0, which currently means Windows XP, Vista, 7, and 8, and the server versions based off of those.
FooSync is in the very early stages of development. The command line client works for limited uses (specifically syncing local paths or mounted Windows shares) but requires manually writing config .xml files, and isn't user friendly yet.
The WPF GUI is being actively worked on.
The first WPFApp was mostly completed, and works for syncing local directories and mounted Windows shares, just like the command-line client. The wizards for editing the config files are unfinished, but with some light editing of .XML config files, it does work, and I've been using it for my day-to-day needs while working on the redesign. It lives in a branch called 'old-WPFApp'.
The new redesign in progress extends functionality to syncing with remote servers in a many-to-many ("M:M") fashion. This code doesn't work yet.
To support this, a network server (FooSync.Daemon) is in progress. It can run as a Windows service, or as a simple process (it can be backgrounded and detached to run as a daemon in Linux). It is also not complete; it currently is read-only.
WPFApp version 1 will be deleted once WPFApp2 (and the network server and any supporting changes in the engine library) is completed.