Duplicati - Free backup software to store backups online with strong encryption. Works with FTP, SSH, WebDAV, OneDrive, Amazon S3, Google Drive and many others.
FileHamster - Personal Revision Control - File Hamster - File and Document Revision, Retrieve and Restore
snaprd - Snaprd is a program that helps you to make snapshot backups using rsync.
ForeverSave - Data loss, caused by application crashes and unintentional overwriting will become history.
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.
AutoArchive - AutoArchive is a simple utility to help create backups more easily.