rsync - rsync is a file transfer program for Unix systems. rsync uses the "rsync algorithm" which provides a very fast method for bringing remote files into sync.
FileHamster - Personal Revision Control - File Hamster - File and Document Revision, Retrieve and Restore
GoodSync - GoodSync provides highly reliable file backup and synchronization for both individuals and businesses.
ForeverSave - Data loss, caused by application crashes and unintentional overwriting will become history.
FreeFileSync - FreeFileSync is a free open source data backup software that helps you synchronize files and folders on Windows, Linux and macOS.
AutoArchive - AutoArchive is a simple utility to help create backups more easily.