Very simple Backup solution has some other ideas. One interesting thing I just noticed is that Cobian Backup (a favorite of those who want the original files and folder structure, and have space for enough versions) has seemingly been reimplemented using .NET Framework (which Duplicati also uses) as Cobian Reflector. For non-Windows, FreeFileSync can sort of do versioned backups. Neither of them supports lots of remote destination types though.