Veeam Backup - Backup and restore VMware and Hyper-V virtual machines with Veeam Backup Free Edition. Unlimited hosts and VMs. Free forever.
Restic - Easy: Doing backups should be a frictionless process, otherwise you are tempted to skip it.
Rubrik - Rubrik delivers instant application availability for recovery, search, cloud, and development.
Duplicati - Free backup software to store backups online with strong encryption. Works with FTP, SSH, WebDAV, OneDrive, Amazon S3, Google Drive and many others.
Zerto - Virtual replication & recovery solution
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.