Unison is a file-synchronization tool for OSX, Unix, 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. Developed by Benjamin C. Pierce
License: Open Source
DirSync Pro is a user-friendly, feature-rich synchronization tool that offers real-time syncing and backup options, while Unison is an open-source solution focusing on efficient file syncing with a robust command line interface. The choice between them depends on whether you prefer a paid, user-friendly option or a free, open-source alternative for more technical use.