Unison is a file-synchronization tool for POSIX-compliant systems (e.g. *BSD, GNU/Linux, macOS) and Windows. It allows two replicas of a collection of files and directories to be stored on different hosts (or different disks on the same host), modified separately, and then brought up to date by propagating the changes in each replica to the other.

Note: if you want to connect to this Flatpak build remotely via SSH, put this in the profile file:

servercmd = flatpak run --command=unison io.github.bcpierce00.unison