GoodSync - GoodSync provides highly reliable file backup and synchronization for both individuals and businesses.
ownCloud - ownCloud is an open source project enabling businesses to host their own cloud storage while maintaining regulatory and compliance needs.
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.
Resilio Sync - Resilient, fast and scalable file synchronization for enterprises and individuals
Syncthing - Syncthing replaces proprietary sync and cloud services with something open, trustworthy and...
Dropbox - Online Sync and File Sharing