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.
Treecomp - TreeComp is a utility to keep 2 directory trees and the files within the directories in sync. Download from this site!
FreeFileSync - FreeFileSync is a free open source data backup software that helps you synchronize files and folders on Windows, Linux and macOS.
GoodSync - GoodSync provides highly reliable file backup and synchronization for both individuals and businesses.
Meld - What is Meld? Meld is a visual diff and merge tool targeted at developers.
Allway Sync - Free File Synchronization, Backup, Data Replication, PC Sync Software, Freeware, File Sync, Data Synchronization Software | Allway Sync – File Synchronization That Works . DownloadAllway Sync – Free Software Downloads, Free File .