rsync, Robocopy, SyncBack, SyncToy, Syncthing, GoodSync, Rclone, Allway Sync, Air Explorer, Bacula, ChronoSync, lsyncd, TeamDrive, FTP Synchronizer, DirSync Pro, Foldermatch, PureSync, grsync, Qtd Sync, Unison File Synchronizer, Toucan, Hoodik, Restic, Kopia, ExamDiff Pro, FullSync, MacDropAny, FBackup, Backer, Bvckup 2, BFileSync, Order66, RoboMirror, MirrorFolder, SyncBreeze, DSynchronize, csync, Synkron, MyWorkDrive, SmartSync Pro, SparkleShare, RsyncOSX, Directory Compare, Create Synchronicity, Backup4all, Sync Folders Pro, SyncFolders, Uranium Backup, Synchredible, Treecomp, RapidCopy, ozSync, DropCopy, jaBuT, Alternate File Move, Yintersync, WinExt Free, @MAX SyncUp, BestSync, Bonkey, Zaloha.sh, OneWaySynchronize, CopyInOrder, Dmailer Sync, SSuite Kronoz Sync-Master, TrayBackup, Immortal Files, Kup Backup System, DiffVue, CleanSync, JFileSync, AllSync by Michael Thummerer Software Design, SmartBackup, WinDataReflector, Syncless, Horodruin, FastBackup, Banckle File Sharing, BatchSync Secure are some alternatives to FreeFileSync.