Bacula is an open-source set of programs that allow you to manage backup, recovery, and verification of data across a network of computers.
Duplicity is a backup program that encrypts and stores data using various backends such as local file systems, SSH, Amazon S3, Rackspace Cloud Files, and more.
Rclone is a command-line program to manage files on cloud storage. It can be used to sync files and directories to and from various cloud storage providers.
Amanda is an open-source backup solution that allows the IT administrator to set up a single master backup server to back up multiple hosts to a single large capacity tape drive.
BorgBackup, or simply Borg, is a deduplicating backup program that also supports compression and encryption. It is designed to be efficient in terms of storage space and speed.