Duplicity B2 Backend BackBlaze B2 is a reasonably cheap cloud hosting service. Duplicity is a backup program. When B2 entered beta, I signed up and wrote a backend to use B2 with duplicity. The source is here, but the backend has been integrated upstream, so any future changes will go there. According to an email thread with Backblaze’s CEO, it’s one of the most used open source integrations with B2.