Arc Transfer

Coming soon to Android, iPhone & iPad, Windows, macOS and Linux

Your files. Straight across.

Arc Transfer sends files of any size, whole folders and your clipboard between every device you own, directly over your own Wi-Fi and encrypted end to end. When you’re apart, turn on Remote transfer and files to your paired devices go through a relay that can’t read them. No account, ever.

Get notified at launch See how it works
  • Direct on your Wi-Fi, relay only if you turn it on
  • 0 accounts
  • 10 GB files, same memory as 10 KB

Four steps, one straight line.

Every transfer follows the same path, and you're in control at the second step.

  1. Find

    Devices on the same network discover each other automatically with mDNS, the same local discovery printers and speakers use. Nothing is looked up online. If a network hides them, scan a QR code or type an address.

  2. Ask

    The receiver sees what's coming and accepts or declines before a single byte is sent. Devices you trust can skip the prompt.

  3. Send

    The file streams device to device over a direct, encrypted connection on your Wi-Fi, in 256 KB chunks, so huge files use the same memory as tiny ones. If the Wi-Fi drops, it picks up where it stopped.

  4. Confirm

    “Sent” appears only after the receiver confirms the file is fully written to disk. No optimistic checkmarks.

One app on everything you own.

  • Android
  • iPhone & iPad
  • Windows
  • macOS
  • Linux

Built once with Kotlin Multiplatform and Compose Multiplatform, so every device gets the same app and the same rules.

Your files stay readable only by your devices.

Direct by default, encrypted every time

Every transfer is encrypted end to end, on your Wi-Fi and through the relay. On the same Wi-Fi, discovery is local mDNS and files go straight between your devices. Remote transfer is off until you turn it on, and even then a device on your Wi-Fi is always reached directly. The relay only forwards scrambled data it has no key for, and it keeps nothing on disk.

No accounts

No sign-up, no email, no login, nothing to breach. Each device has its own key, remembered the first time you trust it, so a device pretending to be yours is caught. For Remote transfer you pair once, by QR code or a six-digit code checked on both screens. Those keys are the only identity Arc Transfer knows.

Consent before bytes

The receiver's yes or no is sent before the payload is read, so an unknown device can't write to your disk. Unexpected requests time out on their own.

Big files and quick copies.

  • Any size

    Photos, videos and documents. A 10 GB video uses the same RAM as a 10 KB note, and lengths are checked exactly, so a cut-off transfer is always caught. Send to several devices at once from one confirmation.

  • Clipboard and links

    Copy a code or a paragraph on one device and send it to another in a tap. Links arrive as something to tap, not a file to open, and only web links are allowed. Clipboard text is never saved to history.

  • Whole folders

    Send a folder with its structure intact. The receiver approves it once, not once per file.

  • Picks up where it stopped

    Lose Wi-Fi 9 GB into a 10 GB file and the transfer resumes from where it stopped, after both devices check the part already received.

  • You choose who can reach you

    Off, trusted devices only, or everyone, with “everyone for 10 minutes” for a new device. Trusted devices skip the prompt; everything else still asks first.

  • Never half a file

    Incoming data lands in a temporary file and is moved into place only after the last byte is saved, so you never open a broken copy.

  • Safe file names

    Names sent by another device are cleaned so they can't escape your downloads folder (directory-traversal protection).

  • Send from where you are

    Use the share sheet on Android. On a computer, right-click a file and choose Arc Transfer, or drop files on the window. You still pick who gets it.

  • Works offline

    On the same network, no internet connection is needed. Great on a plane's hotspot, in a hotel, or in a basement with no signal.

  • No Wi-Fi to share?

    On Android 13 and later, Arc Transfer can make its own local network. The other device joins by scanning a code with its camera. Nothing is shared with the internet.

  • See what really happened

    Real bytes, real speed and real time remaining while it runs, and a history of what you sent and received that survives a restart.

  • Send from anywhere

    Phone on cellular, laptop at home? Turn on Remote transfer and paired devices reach each other across networks, through a relay that can't read your files. It's off until you turn it on.

A protocol you can read in a minute.

One connection per transfer, the same steps on your Wi-Fi and through the relay. Everything after the key exchange is encrypted.

SenderFrameReceiver
Both exchange[public key][nonce]a fresh session key, each way
Sender sends[JSON metadata]name, size, type, all encrypted
[accept | reject]the person decides firstReceiver replies
[resume offer]only if part of the file already arrivedReceiver offers
Sender streams[encrypted chunks]only if accepted, 256 KiB each
[ack-ok | ack-fail]only once it's durable on diskReceiver confirms
  • _airbridge._tcp mDNS service, link-local only
  • ECDH P-256 and AES-256-GCM, a new key every session
  • Device keys pinned on first trust
  • Metadata capped at 1 MiB; payload streamed in 256 KiB chunks
  • Reads bounded by the declared size, never by connection teardown
  • Atomic writes via .airbridge-part, then move
  • Relay forwards ciphertext and holds no keys
  • Kotlin Multiplatform engine, Compose Multiplatform UI

Free on your Wi-Fi. Forever.

Sending between your own devices on your own network costs us nothing to run, so it costs you nothing. No limits, no account, no advertising.

  • Arc Transfer

    Free

    on your Wi-Fi, always

    • Any file size, any number of files
    • Folders, with their structure intact
    • Resume after an interruption
    • Clipboard and links
    • Several recipients at once
    • Works with no router at all

    Nothing here is a trial or a reduced version. It's the product.

  • Optional

    Remote transfer

    $19.99/year

    or $1.99 a month

    • Send to your paired devices anywhere
    • Still encrypted end to end
    • The relay can't read your files
    • Wakes the device you're sending to
    • Picks up again if the connection drops

    Free for 7 days. Nothing is charged during the trial and it doesn't renew on its own — when it ends, it stops.

A transfer across your own Wi-Fi never touches a server of ours. A transfer to a device on the other side of the country has to pass through one, and that costs us bandwidth every month. So the line is simple: free on your Wi-Fi, paid when it has to cross the internet.

Questions, answered.

Do both devices need to be on the same Wi-Fi?

Not if they're paired and you turn on Remote transfer. On the same Wi-Fi, files go directly between your devices. Otherwise they go through a relay that can't read them, and both devices need an internet connection. Remote transfer is off until you turn it on.

What can the relay see?

Encrypted chunks, their sizes and timing, an anonymous routing ID, and the IP addresses of the two connections, as any server would. It doesn't log or store those addresses. It can't see file names, contents, your clipboard or device names, it holds no keys, and it keeps nothing on disk.

Do I need an internet connection?

Not on the same network: discovery and transfers happen entirely on your Wi-Fi. Remote transfer between networks needs a connection.

Can I receive with the app closed?

On Android, yes: Arc Transfer keeps listening in the background, even after a restart, and you can accept from the notification. On a computer it keeps running in the tray when you close the window. On iPhone and iPad, Arc Transfer needs to be open or recently used, and the app tells you so.

Is there a size limit?

Not a practical one. Files stream in small chunks with constant memory, so very large files work the same way as small ones; your storage and network speed are the limits.

Do I need an account?

No. There's nothing to sign up for.

Does Arc Transfer collect data?

Not with the default settings: nothing leaves your network. If you turn on Remote transfer, the relay passes an anonymous routing ID and encrypted data through memory during a transfer and keeps none of it. If you turn on “Help improve Arc Transfer”, the app keeps anonymous reliability counts and cleaned-up crash summaries on your device for 14 days and sends them only when you tap Send. You can view exactly what would be sent, or delete it. File names, contents, clipboard text, IP addresses and device names are never included, and there are no analytics or advertising tools in the app.

What happens if it crashes?

Arc Transfer saves a crash report on your device, with file names, addresses and personal folder names removed. Next time you open it, you can read the whole report and decide whether to share it. Nothing is sent automatically.

What does it cost?

Sending between your devices on your own Wi-Fi is free, with no limits on size, number of files or how often — and it stays that way. Remote transfer, for reaching a paired device that isn't on your network, is $1.99 a month or $19.99 a year after a 7-day free trial. It's the only part that costs us anything to run.

What happens if I stop paying?

Everything on your own Wi-Fi keeps working exactly as before — that was never part of the subscription. Only transfers that would have crossed the internet stop. Nothing is deleted and nothing is held back.

Is the trial really free?

Yes. No card is taken, nothing is charged, and it doesn't turn into a subscription at the end. It simply stops and you decide. You get the whole feature for the seven days, not a cut-down version of it.

When can I get it?

Arc Transfer is coming soon. Email us and we'll let you know when it's ready.

Arc Transfer is coming soon.

Android, iPhone & iPad, Windows, macOS and Linux.

  • Google PlayComing soon
  • App StoreComing soon
  • DesktopComing soon
Get notified at launch