There are lots of tools you can use to back up to Backblaze, including their comsumer backup service.
If you want to sync to B2 specifically with a lightweight tool, check out https://rclone.org/
If you want to sync to B2 specifically with a lightweight tool, check out https://rclone.org/
You can configure any cloud storage backend (B2, S3, GCS ...) and combine it with other utility storage backends, like "crypt" [1], "cache" [2] and "chunker" [3], I highly recommend it to anyone searching for a backup solution.
The only feature I miss from Rclone is automatic directory monitoring and mirroring, which I solved using Syncthing (but forces me to host an additional server for it).
[1] https://rclone.org/crypt/ [2] https://rclone.org/cache/ [3] https://rclone.org/chunker/