Backing up a Mac to Backblaze B2

B2 is storage. It is not a backup program, and it does not come with one. Whatever you choose to run on the Mac is the part that decides whether the bytes up there are worth anything — so this page is about that part, and about the one cost nobody mentions until the bill arrives.

What B2 gives you, and what it does not

A bucket and an API. That is the whole offer, and it is a good one: durable object storage that speaks the S3 protocol, priced per terabyte rather than per seat. What it does not include is a schedule, encryption before upload, a way to know the upload was complete and correct, or any answer at all to the only question that matters — whether what is in the bucket can still become your files again.

So you need something on the Mac. That thing can be a script, and we lay out exactly what a hand-rolled one involves because for a lot of people it is the right answer. Or it can be Backstop, which is a native app that bundles restic 0.19.1 and drives it.

What the setup actually involves

A bucket, set to private

One bucket is enough. If you back up more than one Mac, Backstop can write each into its own folder inside the same bucket rather than making you create and pay attention to several.

An application key

Not your account master key — a scoped application key for that bucket. Backblaze shows the secret exactly once. Backstop puts it in the macOS Keychain and passes it to restic at call time; it is never written into a config file or a plist.

The S3 endpoint

s3.<region>.backblazeb2.com, where the region is the one shown next to your bucket. Backstop offers the template so you do not have to go and find it, and fills the rest in around it.

A repository password

Separate from the B2 credentials, and the one that actually protects the data. It goes in the Keychain too. Backstop makes you write it down during setup, because a repository whose password is only in a Keychain on a Mac that died is not a backup.

What leaves your Mac

Ciphertext, and nothing else. restic encrypts and deduplicates on the Mac before anything is uploaded, so what B2 stores is opaque to Backblaze — and to us. We have no servers in the path and no copy of your key. That also means nobody can recover it for you, which is the honest trade and the reason the password screen is deliberately slow.

After the first run, uploads are incremental and deduplicated: unchanged files are not sent again, and a file that exists twice on your Mac is stored once. What lands in the bucket is a standard restic repository — not a proprietary format with an export button. Getting your files back with no Backstop installed is five commands, printed on our FAQ, and our build runs those exact lines out of that page against a real repository before anything ships.

The part that is not about storage at all

Once a month, Backstop restores real files out of the bucket and compares them byte for byte with the originals still on your Mac. Not a checksum recorded at upload time — the actual files, pulled back down from B2, actually compared. Then it writes down the date and the result.

This matters more with object storage than with a drive on your desk, because everything between you and the bucket is invisible. An upload can truncate. An object can go missing. A credential can expire and turn every run since into a no-op. None of that shows up in a backup log, because backing up never reads what is already there. You find out on the day you need it, which is the worst possible day to find out.

What verification costs, in real numbers

Reading data back out of B2 is egress, and egress is the line item people get surprised by. So here is the arithmetic rather than a reassurance.

Backblaze's published pay-as-you-go rate is $6.95 per TB per month stored, with free egress up to three times your average monthly stored amount, and $0.01/GB beyond that (checked 4 September 2026 — Backblaze publishes current pricing here, and it is their number to change, not ours).

Say you keep 500 GB in B2. That is about $3.48 a month in storage, and your free egress allowance is roughly 1.5 TB. Backstop's monthly read-back verifies a percentage of the stored data that you set, and the restore drill pulls a small number of real files. At a 10% read-back that is 50 GB a month — comfortably inside the free allowance, with room left over for an actual restore.

The number worth watching is not verification. It is the full restore you will one day do: 500 GB down in one month against a 1.5 TB allowance is still free, but a restore much larger than three times your stored average is where a bill appears. That is true of any tool writing to B2. It is worth knowing before you need it rather than during.

When this is the wrong tool

You want an all-in-one consumer service with its own storage included. Backstop has no servers and sells no storage — you bring the bucket and the bill comes from Backblaze. That is more setup, and for some people the wrong shape entirely.
Your Mac is not on macOS 14 or later. Backstop leans on APFS snapshots, the Keychain, TCC and LaunchAgents hard enough that older systems are out.
You already have a working B2 script and you already run restore drills. Then you have solved the real problem. Here is exactly what that setup involves, so you can judge whether we are adding anything.
B2 is your only copy. One destination — anywhere — is one thing going wrong away from nothing. Offsite storage covers fire and theft; it does not cover you deleting something and not noticing for a year.

Before you buy anything

Test the backup you already have. Real commands, no purchase, and it works whether your backup goes to B2, a drive, or Time Machine. Whatever you decide about Backstop afterwards, knowing whether your current backup restores is worth more than the price of this app.

$39, one time Test your current backup first