Restic - Easy: Doing backups should be a frictionless process, otherwise you are tempted to skip it.

CopyQueue - CopyQueue - Copying under control.

Duplicati - Free backup software to store backups online with strong encryption. Works with FTP, SSH, WebDAV, OneDrive, Amazon S3, Google Drive and many others.

Synchromat - Synchromat is file and folder synchronization software for Windows.

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.

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.