rdiff-backup is described as 'Backs up one directory to another, possibly over a network. The target directory ends up a copy of the source directory, but extra reverse diffs are stored in a special subdirectory of that target directory, so you can still recover files lost some time ago' and is an app in the backup & sync category. There are more than 50 alternatives to rdiff-backup for a variety of platforms, including Windows, Mac, Linux, Android and BSD apps. The best rdiff-backup alternative is Duplicati, which is both free and Open Source. Other great apps like rdiff-backup are rsync, Macrium Reflect, TimeShift and Acronis True Image.