Getting Your Backblaze B2 Application Key

File Transfer for Backblaze B2 connects with a key pair you create in your own Backblaze account: a Key ID and an Application Key. It takes about a minute.

This is for B2 Cloud Storage only

Backblaze sells two different products. This app works with B2 Cloud Storage, the object storage service with buckets. It does not work with Backblaze Computer Backup, the desktop backup app that backs up your whole Mac. Your Computer Backup account and its files are not reachable through B2 application keys.

1. Open the Application Keys page

Sign in to Backblaze and go to secure.backblaze.com/app_keys.htm (B2 Cloud Storage ▸ Application Keys in the sidebar). Scroll down and click Add a New Application Key.

Ignore the Master Application Key at the top of that page. It can do far more than this app needs, including deleting buckets. Make a scoped key instead.

The Backblaze B2 Application Keys page with an arrow pointing at the Add a New Application Key button

2. Name the key and set its access

  • Name of Key: anything you'll recognize later, such as Mac File Transfer.
  • Allow access to Bucket(s): pick one bucket, or leave it set to all buckets if you want to browse everything.
  • Type of Access: choose Read and Write. Read Only still lets you download, but uploads, renames, and deletes will fail.
  • The remaining fields are optional. Leave them empty.

Click Create New Key.

The Add Application Key dialog in Backblaze B2 showing the key name, bucket selection, and Read and Write access option

3. Copy both values before you leave the page

Backblaze now shows a keyID and an applicationKey. The application key is displayed once and never again. If you navigate away without saving it, you'll have to create a new key. Store both in a password manager.

Backblaze B2 confirming a new application key was created, showing the keyID and applicationKey values, which appear only once

4. Enter them in the app

In File Transfer for Backblaze B2, open Settings ▸ Account. Paste the keyID into Application Key ID, the applicationKey into Application Key, and click Connect. Your buckets appear in the sidebar.

The credentials are saved in your Mac's Keychain and sent only to Backblaze. See the privacy policy.

The Account tab in File Transfer for Backblaze B2 with the Application Key ID and Application Key fields and a Connect button

If it doesn't connect

  • Check for a stray space at the start or end of either value. Pasting from a note often brings one along.
  • Make sure the two values aren't swapped. The Key ID is the shorter of the two.
  • No buckets listed? The key may be scoped to a single bucket, or the account may have no buckets yet.
  • Uploads failing on a key that downloads fine? It was created as Read Only. Create a new Read and Write key.

Still stuck? Send me the details and I'll help.

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