csync is described as 'lightweight utility to synchronize files between two directories on a system or between multiple systems' and is an app in the Backup & Sync category. There are more than 25 alternatives to csync for a variety of platforms, including Windows, Mac, Linux, PortableApps.com and Google Drive. The best alternative is FreeFileSync, which is both free and Open Source. Other great apps like csync are Duplicati (Free, Open Source), rsync (Free, Open Source), Unison (Free, Open Source) and SyncToy (Free).
Great for synchronizing large collections of media files such as MP3s, Videos, etc... without copying every file. Save time by only copying the files that are new or different. Use "Clone Mode" to synchronize a folder to match a master folder.
FolderMatch is a program that compares directories and files, showing the differences clearly. -Easily, quickly, and reliably compare and synchronize two folders, two drives, or two computers. -Safely backup photos, emails, contacts, and documents.
** IMPORTANT NOTE: This app may not work properly on Android Oreo because of a new change Google has introduced causing a critical feature to fail. I am currently in the process of looking for a fix. Apologies...
BitReplica is a tool for backing up files stored on your Windows PC. It protects your photos, music, documents and any other data from being lost due to a hard drive crash, virus attack or accidental deletion.
cwRsync is a yet another packaging of rsync and Cygwin for Windows. You can use cwRsync for fast remote file backup and synchronization. Rsync uses the rsync algorithm which provides a very fast method for bringing remote files into sync.
Lsyncd watches a local directory trees event monitor interface (inotify or fsevents). It aggregates and combines events for a few seconds and then spawns one (or more) process(es) to synchronize the changes. By default this is rsync.