Getting Started with the S3 Compatible API Getting Started with the S3 Compatible API

Getting Started with the S3 Compatible API

Troy Troy

With the new Backblaze S3 Compatible API, B2 Cloud Storage is now more accessible than ever. You now have the ability to BYOI (Bring Your Own Integration), and if it supports the S3 API then you’re all set!

There are three things you need to connect your integration with the Backblaze S3 Compatible API:

  • S3 Endpoint
  • Application Key
  • Application Key ID 

To find the S3 Endpoint for your account, navigate to the Buckets page of your Backblaze account (Don’t have a Backblaze account? Sign up for an account with 10 GB free here!). In the area for your bucket, you’ll see the S3 Endpoint listed.


Note: Buckets created prior to May 4th, 2020 are not S3 Compatible. If you do not have any S3 Compatible buckets, simply create a new bucket!


For the Application Key ID and Application Key, head to the App Keys page and make a new key. The Master Application Key will not be S3 Compatible, so you’ll want to create a new key and key id by clicking the Add a New Application Key button. Once you’ve made your key, make sure you copy the Application Key ID and Application Key listed in the blue box (you’ll see the S3 Endpoint again too!). Your new key will work with the S3 Compatibility API as well as the B2 Native API. 

Note: If an Application Key is restricted to a bucket, the listAllBucketNames permission is required for compatibility with SDKs and integrations. The listAllBucketNames permission can be enabled upon creation in the web UI or using the b2_create_key API call.


Note: Application Keys created prior to May 4th, 2020 are not S3 Compatible. 

Now you’re ready to enter this information into your application of choice. There are a few things to keep in mind here regarding the naming conventions we use for our S3 Compatibility API. 

1. keyID = Access Key ID or Access Key

Depending on the integration you’re using, you will be prompted for the Access Key ID or Access Key. In our S3 Compatibility API, this is the equivalent of our Application Key ID. You can see in the example here that this is shown at the top of that blue box. 

2. applicationKey = Secret Access Key or Secret Key

Again, this will depend on the application that you’re using, but the Application Key is our equivalent of the Secret Key or Secret Access Key. In our example, this is shown at the bottom of the blue box. 

3. Region is the 2nd part of your S3 Endpoint

Some integrations may need you to specify the region. The region will be the 2nd part of your S3 Endpoint. So if your S3 Endpoint is, this means your region will be us-west-001

4. Only v4 Signatures are currently supported

Our S3 Compatibility API only supports the most recent version of authentication known as the v4, or version 4. If your integration asks you to specify which version (typically v2 or v4), make sure you select v4 as the option. 

Here’s a quick example of what this all looks like in one of our integration partners.


If you’re having issues setting up your application with the S3 Compatibility API, make sure you check out our Knowledge Base which has several guides on many popular integrations like Veeam, IBM Aspera, Quantum, and much more. Our Support Team is also standing by to help get you up and running!