FreeFileSync - FreeFileSync is a free open source data backup software that helps you synchronize files and folders on Windows, Linux and macOS.
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.
SyncBack - Backup software for the PC: powerful, easy to use solution for backing up and synchronising files on a local/network drive, the cloud, FTP server and more.
Bvckup 2 - Bvckup2 is an app that backs up data. You can have your files copied to a folder that will sync with your computer to back up files. It syncs fast and is reliable. Read more about Bvckup 2.
GoodSync - GoodSync provides highly reliable file backup and synchronization for both individuals and businesses.
Synchredible - Synchronize folders and drives with only one click. Easy to use data synchronisation: