Python source code? Yes, it is on https://github.com/borgbackup/borg https://github.com/borgbackup/borg (if that was the question). No cloud? Indeed, borg does

Python source code? Yes, it is on https://github.com/borgbackup/borg https://github.com/borgbackup/borg (if that was the question). No cloud? Indeed, borg does not integrate cloud functionality. You'll either need a directory or a server with ssh and borg to store your backups into. Some people use rclone to clone their borg repos to the cloud.