How to enable FTP and SFTP file transfers for Backblaze B2 Storage Buckets

Backblaze B2 is a cost-effective cloud object storage service designed for storing large amounts of data. However, Backblaze B2 only supports HTTPS and S3-compatible API connections natively—it does not provide built-in FTP or SFTP access. This can create challenges when you need to exchange files with partners, vendors, or automated systems that rely on traditional file transfer protocols.

Couchdrop bridges this gap by adding FTP and SFTP capabilities to your Backblaze B2 storage. This enables your trading partners to securely upload and download files using their existing SFTP clients (like FileZilla or WinSCP) without requiring them to learn new APIs or change their established workflows. When files are transferred through Couchdrop, they are stored directly in your Backblaze B2 bucket—Couchdrop acts as a secure conduit without storing your data.

In this tutorial, you will connect your Backblaze B2 bucket to Couchdrop and configure SFTP access for external file exchange. You will create the necessary credentials in Backblaze, establish the storage connection in Couchdrop, and verify that files can be uploaded and downloaded via SFTP.

When you finish, you will be able to provide secure SFTP credentials to trading partners that allow them to transfer files directly to and from your Backblaze B2 storage using their preferred file transfer tools.

Prerequisites

To complete this tutorial, you will need:

• A Backblaze B2 account with at least one bucket created. You can sign up for a Backblaze account at backblaze.com.
• A Couchdrop account with Admin permissions. You can sign up for a free trial at couchdrop.io/register.
• An SFTP client for testing, such as FileZilla or Cyberduck. You can also use the command-line sftp tool if you prefer.

Step 1 — Creating Application Keys in Backblaze B2

Couchdrop requires application credentials to access your Backblaze B2 bucket. In this step, you will generate an application key and retrieve your account details from Backblaze.

Log in to the Backblaze web console at secure.backblaze.com.

In the left navigation menu under B2 Cloud Storage, click Buckets to view your existing buckets. You will need to note the bucket name you want to connect to Couchdrop. If you do not have a bucket yet, create one now by clicking Create a Bucket, entering a name, and saving.

Next, locate your Bucket ID, which Couchdrop needs to establish the connection. Click on your bucket name in the list to view its details. The Bucket ID appears in the bucket information panel—copy this value and save it for later use.

Navigate to Application Keys in the left sidebar under B2 Cloud Storage. This page displays all application keys for your account.

Click Add a New Application Key to create credentials for Couchdrop. Configure the key settings:

• Name of Key: Enter a descriptive name like couchdrop-sftp-access to identify this key's purpose
• Allow Access to Bucket(s): Select the specific bucket you want to connect to Couchdrop from the dropdown menu
• Type of Access: Select Read and Write to allow both uploading and downloading files through Couchdrop
• Allow List All Bucket Names: Check this box if you need to list multiple buckets through Couchdrop
• File name prefix: Leave this blank unless you want to restrict access to files with a specific prefix
• Duration (seconds): Leave this blank for a key that does not expire, or enter a value if you want the key to expire automatically

Click Create New Key to generate the credentials.

The next screen displays your new application key details. This is the only time you will see the applicationKey value, so copy it immediately:

• keyID: This is your Backblaze Key ID for Couchdrop
• applicationKey: This is your Backblaze Master Key for Couchdrop

You now have the credentials needed to connect Backblaze B2 to Couchdrop. In the next step, you will add Backblaze as a storage connection in Couchdrop.

Step 2 — Connecting Backblaze B2 Storage to Couchdrop

With your Backblaze credentials ready, you will now configure Couchdrop to access your B2 bucket. This creates a storage connection that Couchdrop users can interact with via SFTP.

Log in to your Couchdrop account at my.couchdrop.io.

Click + Create in the top navigation, then select Connect to Storage from the dropdown menu. Alternatively, navigate to Settings > Connections and click + Add Connection.

On the storage selection screen, search for "Backblaze" in the search bar or scroll to find Backblaze B2 in the list of available storage providers. Click Continue to proceed.

Configure the Backblaze B2 connection with the following details:

• Connection Name: Enter a descriptive name for this connection, such as Backblaze Production or B2 Partner Exchange. This name helps you identify the connection when creating users or automations.
• Folder Name: Enter a folder name that will represent this connection in Couchdrop's file system, such as Backblaze or B2-Storage. This is the folder path SFTP users will see when they connect.
• Backblaze Key ID: Paste the keyID value you copied from Backblaze in Step 1
• Backblaze Master Key: Paste the applicationKey value you copied from Backblaze in Step 1
• Your Bucket ID: Paste the Bucket ID you noted in Step 1

After entering all required information, click Test Connection to verify that Couchdrop can access your Backblaze B2 bucket. If the test fails, double-check that you have:

• Copied the credentials correctly without extra spaces
• Created an application key with Read and Write permissions
• Entered the correct Bucket ID (not the bucket name)
• Selected the correct bucket when creating the application key

When the connection test succeeds, you will see a folder browser showing your Backblaze B2 bucket contents. If you want to restrict access to a specific subfolder within the bucket, select it now. This is optional—you can select the root of the bucket if users should access all folders.

Click Save to complete the storage connection setup.

Your Backblaze B2 bucket is now connected to Couchdrop and will appear as a folder in the file system. In the next step, you will create an SFTP user account that can access this storage.

Step 3 — Creating an SFTP User for Backblaze B2 Access

To enable external parties to upload and download files via SFTP, you need to create user accounts with appropriate permissions. In this step, you will create an SFTP user that has access to your Backblaze B2 storage through Couchdrop.

From the Couchdrop dashboard, click + Create in the top navigation and select SFTP User from the menu. Alternatively, navigate to Users in the left sidebar and click + New User.

Configure the new user account with these settings:

• Username: Enter a unique username for this account, such as vendor-upload or partner-b2-access. This is the username the external party will use to connect via SFTP
• Home/Root Directory: Click Select a location and navigate to the Backblaze B2 connection you created in Step 2. Select the folder path where this user should be restricted. The user will not be able to navigate above this directory
• Password: Choose either Autogenerated Password for Couchdrop to create a secure password automatically, or select Custom Password to enter your own. For production use, autogenerated passwords provide stronger security
• Public and Automatic RSA Key Creation: Leave this unchecked unless you specifically need SSH key authentication instead of password authentication

Click Create user to save the account.

The next screen displays the complete connection details for this SFTP user. This information includes:

• Username: The account username
• Password: The password for authentication (only shown once)
• SFTP Endpoint: The connection address in the format sftp://username@<^>your_subdomain<^>.couchdrop.io
• SFTP Private Key and SFTP Public Key: SSH keys if you enabled RSA key creation

You have now created an SFTP user with access to your Backblaze B2 storage through Couchdrop. In the next step, you will test the connection to verify everything works correctly.

Step 4 — Testing SFTP Access to Backblaze B2

Before sharing credentials with external parties, you should verify that the SFTP connection works as expected. In this step, you will use an SFTP client to connect to your Backblaze B2 storage through Couchdrop.

Open your SFTP client. This tutorial uses FileZilla as an example, but the process is similar for other clients like Cyberduck or WinSCP.

In FileZilla, open the Site Manager by clicking File > Site Manager or pressing CTRL+S (Windows/Linux) or CMD+S (Mac).

Click New Site and configure the connection:

• Protocol: Select SFTP - SSH File Transfer Protocol from the dropdown
• Host: Enter your Couchdrop subdomain without the sftp:// prefix or username, such as <^>your_subdomain<^>.couchdrop.io
• Port: Leave this as 22 (the default SFTP port)
• Logon Type: Select Normal
• User: Enter the username you created in Step 3
• Password: Enter the password you copied in Step 3

Click Connect to establish the connection.

Test uploading a file by dragging a test file from your local directory (left panel) to the remote directory (right panel) in FileZilla. The file transfer progress appears in the bottom panel. When the upload completes, verify that the file appears in the remote directory listing.

To confirm the file reached your Backblaze B2 bucket, log in to the Backblaze web console and navigate to your bucket. Click Browse Files to view the bucket contents. The file you uploaded via SFTP should appear in the same folder path you selected in Couchdrop.

Test downloading a file by selecting a file in the remote directory (right panel) in FileZilla and dragging it to your local directory (left panel). Verify that the file downloads successfully and appears in your local folder.

If you encounter connection errors, verify that:

• You are using the correct hostname without sftp:// or the username
• The username and password match exactly what was generated in Couchdrop
• Your firewall or network allows outbound connections on port 22
• You have not exceeded any rate limits or connection restrictions

You have now successfully connected to your Backblaze B2 storage via SFTP through Couchdrop and verified that files can be uploaded and downloaded. You can share these credentials with external parties who need to exchange files with your organization.

Next Steps

In this tutorial, you configured FTP and SFTP access to your Backblaze B2 storage using Couchdrop. You created application credentials in Backblaze B2, connected your bucket to Couchdrop, created an SFTP user account, and tested the connection using an SFTP client.

You can now provide secure SFTP credentials to partners, vendors, or automated systems that need to transfer files to your Backblaze B2 storage. Files transferred through Couchdrop are stored directly in your B2 bucket without intermediate storage, maintaining the cost-effectiveness of Backblaze while adding the file transfer capabilities your partners require.

To expand your file transfer workflows with Backblaze B2, you might want to:

• Configure automated file processing when files arrive in Backblaze using File Actions
• Set up email-based file delivery to Backblaze with Mailboxes
• Create scheduled file transfers between Backblaze and other storage systems using Transfer Automations
• Apply PGP encryption to files before they are stored in Backblaze

For more information on these features, refer to our documentation on File Actions, Mailboxes, and Transfer Automations.