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What is S3-compatible storage — and how to use it for Android photo backup

Updated May 2026 · 7 min read

What is S3?

Amazon S3 (Simple Storage Service) launched in March 2006 as one of the first commercially available cloud infrastructure products. Its core design was deliberately simple: you store objects (files of any type or size) inside named containers called buckets. The API defining how to interact with those buckets — how to upload an object, retrieve it, list the contents of a bucket, delete an object, set permissions — became known as the S3 API.

The S3 API quickly became the de-facto standard for cloud object storage, for the same reason HTTP became the standard for web communication: once enough software was built to speak the protocol, there was enormous value in being compatible with it. A developer who already knows how to write code that talks to S3 does not need to learn a new API for every storage provider they want to use.

Over the following decade and a half, competing providers — Backblaze, Cloudflare, Wasabi, and many others — implemented the same API. Their services are described as "S3-compatible": any tool, library, or app built for Amazon S3 works with them, verbatim, by just changing the endpoint URL and credentials.

Why S3 compatibility matters for photo backup

For photo backup specifically, S3 compatibility delivers three concrete benefits.

App portability. One app — Breazzy — works with a dozen storage providers. You do not need a different app for Backblaze, a different one for Cloudflare, and another for Wasabi. If you decide to switch providers because prices change or a better option emerges, you change the credentials in Breazzy and re-sync. Your photos are standard objects in a standard bucket. Nothing about your workflow changes.

Price competition. Because any S3-compatible provider can be swapped in, they compete on price. Backblaze B2 costs $6/TB/month — roughly a quarter of Amazon S3's $23/TB/month. Cloudflare R2 charges $0 for egress, which matters if you download your photos frequently. iDrive e2 offers promotional pricing well below $6/TB. This competition benefits you directly: the cost of backing up your photos has fallen sharply as more providers entered the market.

No lock-in. Your photos are stored as standard JPEG, HEIC, and MP4 objects in a bucket you own. There is no proprietary container, no export wizard, no waiting for a data-export job to complete. You can download your entire library at any time with any S3-compatible tool. This is fundamentally different from Google Photos, iCloud, or Dropbox, where your photos live inside a service you access, not a storage layer you own.

S3-compatible providers compared for photo backup

For most Breazzy users starting out, Backblaze B2 offers the best combination of low price, simple setup, and ecosystem maturity. Cloudflare R2 is worth considering if you plan to view or share photos directly from your bucket frequently, since its zero-egress pricing means downloads never cost extra. Wasabi's 90-day minimum storage charge makes it less suitable for libraries where photos are frequently deleted, since you pay for 90 days regardless of how long an object is stored.

See the full provider comparison for a detailed breakdown of each option.

How Breazzy uses S3 for Android photo backup

When you connect Breazzy to a storage bucket, you provide an access key ID and a secret key generated by your storage provider. Breazzy uses these credentials to sign each upload request using AWS Signature Version 4 (SigV4) — the authentication protocol that all S3-compatible services understand. The signed request goes directly from your Android phone to your bucket's endpoint over HTTPS.

Critically, Breazzy has no backend server of its own. The photo travels from your phone to your bucket in a single authenticated HTTPS request. Breazzy's servers are never in the path. This means your photos are never stored on, processed by, or visible to Breazzy's infrastructure at any point. The app is purely local logic running on your device.

Breazzy handles chunked uploads for large video files, retry logic for interrupted connections, and incremental sync so only new or modified photos are uploaded on subsequent runs. All of this is implemented against the standard S3 API, which is why it works identically across all supported providers.

To understand the full picture of how Breazzy works, see how Breazzy works.

How to get started with S3 photo backup on Android

Setting up Breazzy with an S3-compatible provider takes about 10 minutes. The steps below use Backblaze B2, but the process is nearly identical for Cloudflare R2 and other providers.

1. Create an account with your chosen provider. For Backblaze B2, go to backblaze.com and sign up. No credit card is required for the 10 GB free tier.
2. Create a private bucket. In the B2 Cloud Storage section of your dashboard, click "Create a Bucket." Name it something like my-android-photos and set visibility to private.
3. Generate an application key. Go to App Keys in your Backblaze account and create a new key scoped to your bucket with read and write permissions. Copy the key ID and application key — you will need both.
4. Install Breazzy and connect. Download Breazzy from the Google Play Store, open it, select your provider (Backblaze B2), and enter your bucket name and key credentials. Breazzy will verify the connection in seconds. Choose your backup folders and tap Start backup.

For a fully illustrated walkthrough, see the Backblaze B2 setup guide. Guides for Cloudflare R2 and Amazon S3 are also available in the providers section.

Frequently asked questions

What does S3-compatible mean?

S3-compatible means a cloud storage service implements the same HTTP API that Amazon S3 defined. Any app built to communicate with Amazon S3 can communicate with an S3-compatible service — Backblaze B2, Cloudflare R2, Wasabi, iDrive e2 — just by changing the endpoint URL and credentials. The underlying operations are identical: PUT to upload an object, GET to retrieve it, LIST to enumerate a bucket's contents.

Which S3 provider is cheapest for photo backup?

For most libraries, Backblaze B2 ($6/TB/month) and iDrive e2 ($2.49/TB/month) offer the lowest per-GB storage rates. Cloudflare R2 costs more per GB ($15/TB/month) but charges nothing for egress — downloads are free — which makes it cheaper in practice if you frequently access your photos. Wasabi charges $6.99/TB/month but enforces a 90-day minimum storage charge per object. Amazon S3 Standard costs roughly $23/TB/month and is the most expensive option for photo storage.

Do I need technical knowledge to use S3 for photo backup?

Not with Breazzy. You need to create a bucket and generate an API key on your provider's website — a 5-minute process done through a standard web UI — then enter those credentials into Breazzy. The app handles all the S3 API calls, authentication signing, chunked uploads, and incremental sync logic behind the scenes. No command line, no code, no AWS documentation required.