Overview and quick start

From README.md in the repository, rendered 2026-10-12.

Alpha software — do not use for production data. Varsto is in early development. Bugs can cause data loss or corruption, file formats and protocols may change without a migration path, and the cryptography has not been independently audited yet. Do not use it as the only copy of anything. You are responsible for keeping your own backups and for checking that you can restore from them. Each released storage-format version keeps a reader; see docs/spec/format-versions.md.

"Varsto" is a working name and may change before the first public release.

Source: https://github.com/janttsu/varsto (issues and pull requests welcome). Website: https://varsto.net.

Varsto is an end-to-end encrypted file sync, sharing and backup app that uses your own devices and storage services of your choice. You bring the storage; the app does the rest.

Goals

• Bring your own storage. S3-compatible keys, any rclone-compatible remote, a local folder, or removable disks (for example old hard drives in a USB dock). Cold storage such as Glacier is understood and used for rarely accessed data.
• No one to trust, and no shortcuts. All content, file names and metadata are encrypted on your devices, and keys stay with you. External disks and cloud providers see opaque blocks only. Designed for post-quantum security (hybrid classical + post-quantum). Security is never traded for speed: there is no weaker "fast mode". Hardware security keys (FIDO2 / YubiKey), special-protected folders, and a recovery kit you store physically in several places. See docs/architecture/security-principles.md.
• No tracker, no account, no vendor cloud. Devices find each other on the local network, through a rendezvous record in your own storage, and through a rendezvous record in your own storage (a DHT fallback is designed, not built). Designed to avoid single points of failure.
• Fast, block-level sync. Files are split into blocks whose size follows the file; only changed blocks move, and the blocks of small files travel together in packs, so a folder of thousands of notes is a few objects on the storage, not thousands. Peer-to-peer transfer between your own devices, also offline over a LAN, with the cloud brought up to date when you are back online.
• Safety nets. Version history, trash (optionally on cold storage), durability policies with alerts, peer-to-peer transfer between your devices on the LAN and over the internet, zstd compression before encryption, Strongroom folders that open only with a FIDO2 security key (libfido2 tools), a printable recovery kit (24 words, 2-of-3 shares), geographic location awareness, and provider-independent recovery. What the design tolerates, and what it does not, is listed in docs/failure-model.md.
• Clients. Linux, Windows, macOS, Android, iOS; a command line on Linux, macOS and Windows; an MCP server so you can manage and organise files by talking to a local or cloud AI of your choice.

None of this is finished. See docs/architecture for the design principles and docs/spec for the status of the format and protocol specifications.

Status

Alpha (0.0.1-alpha.12): the core works on Linux, macOS and Windows (since alpha.9 the macOS and Windows packages are built and tested on GitHub-hosted runners on every change, the Windows one on Windows Server 2025; they have not been through the manual checklists on real machines yet) as a background service with a tray or menu-bar app, a local desktop interface, a command line, and an Android shell (sideloadable APK). Implemented: small blocks stored in packs (fewer objects and requests on buckets), the interface, tray and website in English, Finnish and Swedish, organizations for business use (administrators, device approval, removing a person, a signed log), peer-to-peer and the background service on by default, a default durability policy, block sizes that follow the file size, encrypted chunked sync through any directory, S3-compatible bucket or rclone remote, signed per-device ledger and convergence between devices that are never online together, conflict copies and trash, selective sync with placeholders, transferrer disks, untrusted replica devices, folder sharing with another user by key (sealed to a post-quantum request code), encrypted thumbnails, self-update, hybrid Ed25519 + ML-DSA-65 signatures, an MCP server with per-folder grants, durability policies with alerts, peer-to-peer transfer between your devices on the LAN and over the internet (QUIC with hole punching, and a relay through one of your own reachable devices when punching fails; tested on localhost and on the maintainer's own networks only), zstd compression before encryption, Strongroom folders that open only with a FIDO2 security key (libfido2 tools), a printable recovery kit (24 words, 2-of-3 shares), a pool of removable disks that are filled, checked, ejected and recognised when they come back (with "attach this disk" prompts for files that are on a disk that is away), and Varsto's own last-accessed record with cost advice from open price data. It chunks and encrypts files, stores them in a local-directory storage (a disk, a removable disk or a network mount), keeps a signed per-device ledger in that storage, and syncs a folder between devices that are never online at the same time, with conflict copies and a trash. See docs/spec/alpha-0-format.md for what it does and does not do. The iOS app (apps/ios, crates/varsto-ffi) is built and launched on the iOS Simulator in CI but has not run on a real device yet; there is no vendor relay for vaults without a reachable device, and no audit yet.

Quick start

cargo build --release                      # produces target/release/varsto
varsto desktop                             # local graphical interface in your browser (127.0.0.1 only)
export VARSTO_PASSPHRASE='a long passphrase'
varsto --home ~/.varsto-laptop init --name laptop            # prints the vault key once
varsto --home ~/.varsto-laptop storage add-local box /mnt/box
varsto --home ~/.varsto-laptop storage add-s3 cloud --endpoint https://s3.fr-par.scw.cloud --region fr-par --bucket my-bucket --access-key-id AK... --secret-access-key ...
varsto --home ~/.varsto-laptop storage add-rclone hetzner storagebox:varsto   # any rclone remote
varsto --home ~/.varsto-laptop folder add docs ~/Documents/synced
varsto --home ~/.varsto-laptop sync
varsto install                             # Linux: varsto on PATH, tray at login, menu entry. Background sync (systemd user unit / macOS launch agent) is set up by any command once a vault exists; varsto uninstall turns it off
varsto tray                                # Linux/Windows: tray icon + background service (macOS: Varsto.app)
varsto update --check                      # self-update from the download page (also checked automatically)
varsto transfers --watch                   # uploads, downloads and peer traffic running now

# on another device that can reach the same storage:
varsto --home ~/.varsto-desk join --name desk --vault-key <hex> --storage-path /mnt/box
varsto --home ~/.varsto-desk folder attach docs ~/synced
varsto --home ~/.varsto-desk sync
varsto --home ~/.varsto-desk status --json
varsto --home ~/.varsto-desk fsck --verify

# recovery kit: the vault key as 24 words (and 2-of-3 shares) for paper or metal
varsto --home ~/.varsto-laptop recovery kit --shares

# a Strongroom: the folder key exists only while your security key is touched (needs fido2-cred/fido2-assert)
varsto --home ~/.varsto-laptop strongroom create taxes ~/Taxes
varsto --home ~/.varsto-laptop strongroom unlock taxes --minutes 15

# peer-to-peer is on by default (port 17893): devices exchange encrypted blocks directly (LAN
# automatically; internet through NAT, with one of your own reachable devices as the relay when
# hole punching fails); `varsto p2p disable` turns it off
varsto --home ~/.varsto-server p2p enable --public 203.0.113.5:17893   # reachable: relays for the others
varsto --home ~/.varsto-laptop p2p status   # NAT guess, public address, path to every peer
varsto --home ~/.varsto-laptop p2p traffic --watch   # live speed, totals and path per peer

# a durability policy: two cloud copies, one at home, verified within 30 days; exit code 0/1/2/3.
# A folder without its own policy uses the default: 1 copy on any storage, 1 in external storage,
# 1 on your own devices or disks, verified by another device within 30 days.
varsto --home ~/.varsto-laptop policy set docs --min-copies 2 --place cloud=2 --place home=1 --verified-within-days 30
varsto --home ~/.varsto-laptop policy check

# let an AI assistant read, analyse and (with --write) reorganise one folder
varsto --home ~/.varsto-laptop mcp grant docs
varsto --home ~/.varsto-laptop mcp          # MCP over stdio; point Claude Desktop, Claude Code or any MCP client at this command

# a lost or stolen device: remove it from another device (new vault keys for everything written
# afterwards) and order it to wipe itself when it next reaches a storage; then print a new recovery kit
varsto --home ~/.varsto-laptop device list
varsto --home ~/.varsto-laptop device revoke phone --wipe --yes
varsto --home ~/.varsto-laptop org create --name "Acme" --user alice   # business use: administrators, approvals, a signed log
varsto --home ~/.varsto-laptop org remove-user bob --wipe --yes       # every device of a person, in one step

# a pool of removable disks: fill, check, eject, retire; files on a disk that is away say "attach disk data-01 (shelf)"
varsto storage add-pool shelf --place shelf
varsto disk add /media/me/data-01 --pool shelf --label data-01
varsto disk list && varsto disk check data-01 --full && varsto disk eject data-01

# selective sync, transferrer disks, replicas and sharing:
varsto folder attach docs ~/synced --selective && varsto folder files docs && varsto folder fetch docs big.mp4
varsto paths free ~/synced/big.mp4 && varsto open-placeholder ~/synced/big.mp4.varsto-placeholder  # what the file-manager actions run
varsto verify-release varsto-<version>-x86_64-unknown-linux-musl.tar.gz --github  # check a download against the signed SHA256SUMS
varsto storage add-local stick /media/usb --carrier       # carries only what the other device lacks
varsto replica token                                      # give to an untrusted backup device
varsto --home ~/.varsto-replica replica init --name nas --token <t> --source /mnt/shared --target /mnt/nas/varsto
varsto share create docs                                  # token for another Varsto user
varsto --home ~/.varsto-shared share accept --name laptop --token <t> --storage-path /mnt/shared

Test data only. Keep your own backups.

Repository layout

Licence

Varsto is source-available, not open source. It is licensed under the PolyForm Shield License 1.0.0: you may use it for any purpose, privately or in a company, except for providing a product that competes with it. It may not be sold, repackaged or rebranded as a competing product; redistribution of unmodified copies under the licence is allowed. The name and logo are covered separately by TRADEMARK.md. Storage formats and protocols are intended to be openly specified so that your data stays recoverable.

Contributing, security and testing

• CONTRIBUTING.md
• SECURITY.md
• TESTING.md