SQZ Atlas documentation

SQZ packs files and folders into one small .sqz archive, stores repeated data once, and checks every file with BLAKE3 when you restore it. SQZ Backup, a preview, keeps encrypted, versioned copies of your folders in a separate repository, from the command line or a desktop app for Windows and macOS.

DownloadThe Windows package, the desktop app, and the extractor for Linux and macOS. Quick startPack, test and restore a folder in five commands. Create and extractEverything about .sqz archives. Pick a modeFast, Smart, Balanced or Max: what each trades. Windows right-click menuCompress and extract from Explorer. Desktop backup appScheduled, encrypted backups for Windows and macOS. Conversation vaultSave AI conversations and let Claude or ChatGPT search them. Encrypted backupsThe sqz backup preview, step by step. Command referenceEvery command and option on one page.

Two tools on one core#

SQZ Atlas is one lossless storage layer with two products on top of it:

Product	What you get	Status
SQZ Archive	A portable `.sqz` file for packing, sharing and keeping snapshots of a folder. Checked for corruption, not encrypted.	Available
SQZ Backup	An encrypted, incremental backup repository (`sqz backup`): a folder or bucket of immutable files that many snapshots share, with retention, pruning, replicas and restore drills. The desktop app runs it on a schedule for you.	Preview

Both use the same core: content-defined chunking, exact deduplication with BLAKE3 fingerprints, a codec picked per block, and a check of every restored byte.

What makes SQZ different#

Duplicates are stored once. Identical pieces of data, inside one file, across files, or across snapshots, are kept once and pointed to.
Already-compressed files get smaller. In Balanced, Smart and Max modes SQZ opens up PNG, ZIP, Office, PDF, gzip and JPEG files, compresses what is inside better, and rebuilds the original bytes exactly on extraction. It only does this when it has proved the rebuild is bit-exact.
Every restore is verified. Each file is checked against its BLAKE3 digest before it is written under its real name. Existing files are never overwritten.
Memory stays bounded. Packing and extraction stream, so you can pack more data than you have RAM.
You know the cost first. sqz estimate predicts time, size and memory from a sample of your real data.

Where things stand#

SQZ is under active development. These docs describe the current development build (it reports itself as sqz 0.9.1 and writes archive format v7). Some parts are newer than others, and the docs say so where it matters:

Tested Archives, all four modes, snapshots, ZIP export, sqz-extract, estimates, and the Windows right-click menu (tried on a real Windows PC in September 2026).
Preview sqz backup. The repository format may still change, so keep another copy of anything irreplaceable.
Early preview The SQZ Backup desktop app (version 0.1.0). Its schedules and saved passwords have been tested on Linux only so far, not yet on a real Windows PC or Mac.
Early preview The conversation vault, an MCP connector that lets Claude, ChatGPT or Codex save and search AI conversations you keep in an encrypted SQZ repository. Connecting Claude to the hosted relay has been tried end to end on a real computer, and ChatGPT and Codex have been tried for saving and searching conversations.
Not yet tried for real Backups to a real S3 bucket (tested only against a simulated server), and parts of the Windows backup features (shadow copies, the change journal, Windows metadata), which are still being tested on real Windows.

Find your way#

New to SQZ: read the Quick start, then Modes and tuning.
On Windows and prefer clicking: see the right-click menu.
Sending an archive to someone: see Sharing archives.
Want backups without a terminal: the desktop app.
Want an assistant that can look up your saved conversations: the conversation vault.
Setting up backups from the command line: start with Backup basics and read the Security model.
Want the details: How it works, Integrity and Format and compatibility.