GoodSync - GoodSync provides highly reliable file backup and synchronization for both individuals and businesses.
Clonezilla - Clonezilla is a suite of software that's designed to allow you to back-up and image new hard drives with your data.
Syncthing - Syncthing replaces proprietary sync and cloud services with something open, trustworthy and...
Macrium Reflect - Macrium Software - the creators of Macrium Reflect backup, imaging and cloning software.
arRsync - arRsync is a tool that is designed for macOS that is used for transferring and synchronizing files between a computer and a storage drive.
AOMEI Backupper - AOMEI Backupper is a software created to help a person backup, restore, clone, and sync their entire Windows system.