rsync.net also supports borg[1], which is how I use it. They also have/had a special pricing for borg users[2]
1: http://borgbackup.readthedocs.io/en/stable/ 2: https://www.rsync.net/products/attic.html
1: http://borgbackup.readthedocs.io/en/stable/ 2: https://www.rsync.net/products/attic.html
It takes your plaintext files and directories, chops them into gpg-encrypted chunks with encrypted, random filenames, and will upload (and maintain) them, with an efficient, changes-only update, to any SFTP/SSH capable server.
My understanding is that the reason people are using borg instead of duplicity is that duplicity forces you to re-upload your entire backup set every month or two or three, depending on how often you update ... and borg just lets you keep updating the remote copy forever.