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Cyberduck Help / Howto / Backblaze B2

B2 Cloud Storage. Backblaze B2 Cloud Storage works similar to Amazon S3 or Microsoft Azure, allowing you to store unlimited data in the cloud. But does it for 1/4th the cost.

Connecting to Backblaze B2

Obtain the login credentials from Choose App Keys on the sidebar and generate a new application key. Once you have your credentials, choose B2 Cloud Storage from the list of protocols when editing a bookmark or use the b2:// scheme when using the CLI.

Authenticating using master key

  • The Master Application Key for an account can be found at the top of the App Keys page of the Backblaze website once you signed in.
  • The key for your account has complete access but will become invalid if you generate a new one.
  • The key information is only shown when generating the key and is not shown again, so make sure you save the credentials in a secure location if you plan on using this more than once.

Use your Account ID and Master Application Key to log in.

Authenticating using application key

How to create application keys

  1. Use the Backblaze website and sign in to your account
  2. Click on App Keys in the left-hand menu
  3. Select Add a New Application Key
  4. Specify the key settings and permissions and click on Create New Key
  5. After the Application Key is created, a blue panel is displayed containing the key ID and application Key for the newly generated key.

Note: The key information will only appear once. Copy the information somewhere safe for later retrieval.

Use your key ID and application Key to log in. The application key can be restricted to a single bucket.

Cyberduck CLI

You can list all buckets with Cyberduck CLI using

duck --username <application key> --list b2:/

Refer to the Cyberduck CLI documentation for more operations.

Using S3 compatible API

  • Download the Backblaze B2 (S3 API) for preconfigured settings.

Buckets created prior to May 4th, 2020 are not S3 compatible and cannot be accessed


Creating Buckets

Choose File → New Folder to create a new bucket in the root of the browser.

Bucket names, notably:

  • must be between 6 and 50 characters long;
  • can only consist of alphanumeric characters or "-";
  • are case insensitive;
  • are globally uniques (i.e. across all Backblaze accounts);
  • cannot begin with "b2-" (reserved for Backblaze use).


Setting it to allPrivate means that every download requires an authorization token.


Setting it to allPublic means that everybody is allowed to download the files in the bucket.

File Versioning

You can view all revisions of a file in the browser by choosing View → Show Hidden Files.

Authorized URL

Create an authorized URL to make files available publicly. Choose File → Share…. The shared URL expires in 7 days.

Large File Uploads

Files larger than 200MB are split into 100MB chunks and uploaded with multiple connections. The number of connections used can be limited using the toggle in the lower right of the transfer window.

Large uploads can be resumed when interrupted.

Unfinished large uploads

You can view unfinished large uploads in the browser by choosing View → Show Hidden Files.


If you want to have the SHA1 checksum set in the file info for the large file upload in large_file_sha1 make sure to check Preferences → Transfers → Checksum → Uploads → Verify checksum.

Edit Bucket Type

New buckets are private by default, meaning that you need a bucket authorization token to download the files. You can allow public access to files by opening the ACL tab in the ''Info'' panel and choose Everyone → Read.

Edit Bucket Lifecycle Rules

Retries for failed file transfers

The number of times a retry attempt is made upon a failure such as 503 Service Unavailable depends on the setting in Preferences → Connection → Repeat failed networking tasks → Number of retries.

Known Limitations

Rename and move files

Not supported. In version 7 or later.


Last modified on Jun 28, 2021 at 12:15:51 PM Last modified on Jun 28, 2021 12:15:51 PM

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