backdown
Public beta · Out now for Linux, macOS and Windows

Backup that thinks.

BackDown copies your drives like any good backup tool, then tells you what's on them: what's duplicated, what each folder actually is, where it came from, and which drives are safe to wipe. Every claim is backed by a hash.

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Report overview: six drives with 15.2 TB and 26.9 million files, including 5.9 TB of redundant bytes.
Everything you have, at a glance Every drive, how full it is, how many files it holds, and how much of it is redundant.
Wipe verdicts: Seagate 2TB is safe to wipe, WD Passport and old-laptop need their unique files copied first, and MacBook-HD is waiting for hash proof.
A verdict for every drive Safe to wipe, copy first, or still hashing, with the exact unique bytes behind each call.
Size tree of an 18 TB archive drive, with Backups expanded to show two Time Machine sets.
See where the bytes are An interactive size tree for every drive, down to the folders that matter.
Table of duplicate folder pairs across drives, largest first.
Duplicates across every drive Folder pairs that share files, between drives and within one, sorted by the space you could reclaim.
Hash verification per drive: Seagate 2TB 100%, old-laptop 99.1%, WD Passport 81.1%.
Hash-verified, folder by folder How much of each drive has a SHA-256-identical copy elsewhere, and exactly what doesn't.
Live dashboard: 14.8 million files indexed, 1.32 TB hashed, indexer and hasher running.
Watch it work Live progress for indexing, hashing, copying and mirrors, with the load on every disk.

Real BackDown screens, shown with demo data.

How it works

Plug in everything. Get answers, not a vault.

Backup tools answer "can I restore this file?" BackDown also answers "what do I have, what's duplicated, and what's safe to delete?"

Point it at every drive you own

Old laptops, NAS shares, the USB disk in the drawer. Scanning only ever reads them, a drive that isn't mounted can be mounted read-only for you, and each drive's health follows its serial number from port to port.

It indexes, hashes and recognises

Tiered hashing checks size first, then a quick sample, then a full SHA-256, so it only fully reads files that could be duplicates. If a drive disconnects or the machine reboots, you lose the file in flight, not the night.

You get a verdict for every drive

What's on it, what each folder is, what's duplicated across every source, and a verdict: safe to wipe, or copy these 212 GB first. Nothing is deleted without a verified copy.

Where it came from

Built on 27 million files and a drawer of old drives.

BackDown began as a one-off job: consolidate years of old disks onto one archive and wipe the rest. The hard part was never copying bytes.

Five of six drives held generations of the same data. The most valuable thing on them, a mail server's archive, only turned up by reading the shell script that once backed it up. And 5.9 TB of the biggest drive was quietly duplicating itself.

No backup tool would have told us any of that. So we built one that does.

27M
files indexed, with every job resumable when a USB drive dropped off the bus
15 TB
of storage read and hashed, with source drives mounted read-only throughout
5.9 TB
of the biggest drive found duplicating itself
3
drives wiped, each only after every byte was hash-verified elsewhere

Hear when 1.0 is out.

The 1.0 beta is out now for Linux, macOS and Windows. Leave your email and we'll send one message when the final version is out.

You're on the list. We'll email you once, when it's ready.

That email address didn't work. Check it and try again.

One email when it's ready. We never share your address.