DropSync a simple application for the macintosh which helps you keep folders backed up and/or synchronized. It’s based on the powerful unix utility rsync which transfers only the parts of files that have changed, so it’s especially good for backups over a network.
What DropSync provides is what rsync lacks, a powerful graphical interface. It lets you setup multiple places to store data and tracks the folders or files you want to sync with each location. Add new items to sync with drag n drop simplicity. DropSync also generates previews of every sync so you can inspect what it is about to do before committing.