Your files.
Your devices.

Yes. There is no price, no account and no subscription. It is free for personal and non-commercial use under the PolyForm Strict License, so using it for a business or at work is not covered; you can read the source, but it is not open source.

A dedicated server is optional. A computer you already own can be the hub, or you can run one with Docker. Phones and tablets connect to a hub; they cannot act as one.

Your devices keep complete copies of the folders they chose. Folders no device chose and the history live only on the hub, unless you turned on the optional full backup on a desktop or server. Movies & TV stays only on the hub: it keeps no history and the backup skips it, so keep your own copy of your video files. A desktop or server with a complete copy of every shared folder can take over as the new hub, with a fresh history.

Sync also carries file deletions between ordinary folder copies. Retained history offers a way back, but keep an independent backup. Arca’s optional full hub backup is off by default and runs on a desktop or server, separately from working copies; it does not include Movies & TV.

Only you and the devices you pair: there is no company server in the middle and no telemetry. If you add a TMDB key, the hub sends the titles and years of your movies and shows to TMDB for posters and details. The desktop app checks GitHub for signed updates, and Open in Maps on a photo opens Google Maps. Arca is not end-to-end encrypted: paired devices are trusted with your files and a local network without HTTPS carries plain HTTP, so if you cannot trust your network, use a private network such as Tailscale.

On your hub and on the devices that sync them, as ordinary files any app can open: desktop copies in folders you choose, phone copies in app storage. The hub’s history and optional backup use Arca’s own format. Your own disks set the capacity.

No. Each device chooses whole folders independently, and the folders you sync download as complete files, ready for offline use. Movies & TV stays on the hub and streams; download a single title when you want it offline. A linked phone album adds its photos to a shared folder, and that phone then keeps the complete folder in app storage like any other device.

To exchange changes and to stream. Once a folder finishes syncing, its local files work offline, and edits wait until the hub is reachable again. Movies & TV and everything on arca TV stream from the hub, so they need it, except a title you downloaded beforehand. An always-on hub keeps all of it within reach.

Yes, if your device can reach the hub. Arca has no public relay, so away from home you need a private network you control, such as Tailscale (a separate service you set up yourself), or your own HTTPS address.

Dropbox, iCloud and Google Drive keep your files on a company’s servers; Nextcloud is a self-hosted platform for many people; Syncthing syncs device to device, with no hub. Arca keeps complete copies of the folders each device chooses, around a hub you run that keeps their history. It has no accounts or per-person permissions, so it suits one person or a group that trusts each other; for per-person sharing or no setup at all, those tools may suit you better.

For one person, or a household that trusts each other, it covers the same ground on your own hardware: photo and video uploads from your phone, a music and podcast library, and movies and shows with posters and Watch next on your laptop, phone and TV. It has no face recognition or AI search, no sharing links for people outside your devices, and it never re-encodes video: a file whose audio a device cannot play gets a compatible audio track.

Link a phone album to a hub folder. Arca uploads new photos and videos without recompressing the originals; browse them by date on desktop or the web. Deleting from your phone’s gallery keeps the uploaded files, and hub changes never write back to your Photos library. Deleting a photo in Arca’s shared gallery removes it from every device’s Arca copy, and it stays recoverable while history is kept.

Choose Set up as library… → Audio on a hub folder. Every device that keeps it browses artists, albums, playlists and recent plays and plays its own complete copy, offline too, on desktop, the web, Android and Android Auto; iPhone browses it and opens tracks in other apps for now. The playlists you make are saved as ordinary files in that folder. An Android app installed outside the Play Store needs Unknown sources turned on in Android Auto’s developer settings.

Choose Set up as library… → Movies & TV on a hub folder. The hub names movies and shows from their files, and with your own free TMDB key adds posters, overviews, ratings and cast. Every device streams from the hub without re-encoding the video, picking up where you left off on another; the phone and the desktop app can download a title to watch offline, and arca TV plays it on your television.

Background work follows iOS and Android scheduling limits. Arca also resumes work when you open it. Keep the app open for a large first upload; background sync is not continuous.

Yes, for as long as the folder’s history keeps it: 30 days by default, adjustable per folder. Restoring needs the hub to be reachable and adds a new version, leaving earlier history intact. Conflicting edits are kept as separate versions for you to review.

The desktop app updates itself from signed releases. Update a Docker server by pulling the new image; Android updates through Google Play. Check the release notes for any requirement to update the hub and its devices together.