They don't have their own client offering, but super-easy to roll your own with their B2 cloud service. There's support for backblaze targets in duplicity, hashbackup, restic and rclone -- my org uses it as a special remote for git-annex, and also use it to back up our synology units (see: https://www.backblaze.com/b2/integrations.html).

2TB would cost you about $10/month for the storage ($0.005/GB), plus $0.01/GB for downloads.