Duplicati

Duplicati runs scheduled, encrypted, incremental backups from a friendly web interface to a long list of destinations — S3-compatible storage, WebDAV, SFTP and most consumer clouds.

The web UI makes it the most approachable of the serious backup tools, though long-time users will tell you to test restores regularly and keep the database maintenance in mind on very large backup sets. Encryption happens before upload, so the storage provider never sees plaintext.

A good first backup tool for people who want set-and-forget scheduling without learning a CLI.