GoodSync - GoodSync provides highly reliable file backup and synchronization for both individuals and businesses.
Duplicati - Free backup software to store backups online with strong encryption. Works with FTP, SSH, WebDAV, OneDrive, Amazon S3, Google Drive and many others.
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.
Online Vault Backup - Online Vault Backup is a cloud storage service that allows you backup your data while having unlimited storage.
Syncthing - Syncthing replaces proprietary sync and cloud services with something open, trustworthy and...
Rebel Backup - Rebel Backup lets you make encrypted backups of your important files to Dropbox or Google Drive.