For using Backblaze B2 as a special remote, there are currently three
choices:

* Using [[special_remotes/rclone]]  
  (Actively maintained)

* Backblaze B2 supports supports the same API as Amazon S3, so
  git-annex's built-in [[S3 special remote|special_remotes/S3]] can be used
  with it. 

  However, it needs S3 version 4 signatures, which are only supported by
  git-annex 8.20200508 and newer.

  Here is how to set up the special remote:

        git annex initremote backblaze type=S3 signature=v4 host=$endpoint bucket=$bucketid protocol=https

  Remember to replace $endpoint with the actual backblaze endpoint and $bucketid with
  the bucketid.

* A dedicated special remote, <https://github.com/encryptio/git-annex-remote-b2>  
  (Last updated 2016)

At this time it's not clear which is better, so if you find one works
better than the other, please comment below.