---
title: Connect Backblaze B2
description: "Create a Backblaze B2 application key scoped to your bucket, find your S3 endpoint, and connect your B2 buckets to quickS3 through the S3 API."
section: Connections
order: 60
audience: [owner]
status: published
lastVerified: 2026-09-15
sources:
  - web/src/components/app/provider-connections/ConnectionFormCard.tsx
  - src/objects/routes/providers.cors.ts
  - src/objects/routes/providers.bucket-create.ts
---

quickS3 connects to B2 through its S3-compatible API. You need an application key and your bucket's S3 endpoint.

## 1. Create an application key

In the Backblaze web console, open **Application Keys** and select **Add a New Application Key**.

- Give it a name like `quickS3`.
- Under **Allow access to Bucket(s)**, pick the bucket your team will use.
- Choose **Read and Write**, or **Read Only** for a read-only connection.

Copy the **keyID** and **applicationKey** straight away. Backblaze only shows the application key once. Don't use your account's master application key: B2's S3 API doesn't accept it.

## 2. Find the endpoint

Open **Buckets** in the Backblaze console. Each bucket shows an **Endpoint** like `s3.eu-central-003.backblazeb2.com`. Add `https://` in front when you paste it into quickS3.

## 3. Add the connection

1. In quickS3, open **Connections**, select **New connection**, and pick **Backblaze B2**.
2. Enter a **Name**.
3. Paste the **Endpoint**, for example `https://s3.eu-central-003.backblazeb2.com`.
4. In **Bucket scopes**, type the bucket name. A key limited to one bucket can't list the others, so quickS3 needs the name.
5. Paste the keyID into **Key ID** and the applicationKey into **Application key**.
6. Keep CORS updates on and select **Connect provider**.

Then select **Test connection**. You want **Connection verified** with "CORS allows direct uploads".

All your buckets in one B2 account share a region, so one connection usually covers them. If you limited the key to one bucket, the connection only reaches that bucket.

## If uploads are blocked by CORS

B2 keeps two separate sets of CORS rules: one for its native API and one for its S3 API. quickS3 uses the S3 set. If the test warns about CORS, check that the key is allowed to change bucket settings, or add the rule to the S3-compatible CORS rules yourself: origin `https://quicks3.com`, methods `GET`, `HEAD`, and `PUT`, all headers allowed, and `ETag` exposed. Backblaze explains the two rule sets in its [CORS rules guide](https://www.backblaze.com/docs/cloud-storage-cross-origin-resource-sharing-rules).

## Creating buckets

The **Create bucket** button needs a key that can create buckets, which means a key not limited to one bucket. If you only need the buckets you already have, keep the narrower key and create new buckets in the Backblaze console.