PairOnce

MAC ↔ WINDOWS · FILES

Transfer files between a Mac and a Windows PC, wirelessly, in the browser

Open paironce.com on both computers, click Enter a code on one and type the six digits the other shows, then choose files on the sender and click Accept and Save on the receiver: no cable, no app, no account.

The file goes straight between the two computers, encrypted end to end, over the same Wi-Fi or across the internet, in either direction.

Chrome, Edge or Firefox on the receiving computer takes up to 2 GB per file.

Step by step

  1. Open PairOnce on both computers. Go to paironce.com on the Mac and on the Windows PC. For files over 50 MB, the receiving computer uses Chrome, Edge or Firefox.
  2. Pair them once. One computer shows a QR code and a six-digit code. On the other, click Enter a code and type the six digits; a code works once and lasts 10 minutes. Check that both screens show the same safety code, then click Approve device on the computer that showed the code. On the same Wi-Fi you can skip the code: with PairOnce open on both, the other computer appears under On this Wi-Fi; select Connect and check the safety code as usual.
  3. Choose the files on the sending computer. Click Choose files or drop files on the page: up to 100 files and 10 GB in total at a time, and up to 2 GB for each file.
  4. Accept and save on the receiving computer. Click Accept for each file, then Save. It lands in Downloads, on a Mac or on Windows. Click I saved it so the sender knows it arrived.
  5. Next time, just connect. The other computer is now listed under Your devices: open PairOnce on both and click Connect, with no new code.

Why not AirDrop or a cable?

AirDrop works only between Apple devices, so it cannot reach a Windows PC. A cable is awkward too: a USB drive has to be formatted as exFAT for both systems to read and write it, and a drive formatted the usual way for one system is read-only or unreadable on the other. PairOnce needs only the two browsers.

Limits, and when this is not the right tool

  • A file can be up to 2 GB over a direct connection when the receiving browser saves straight to disk (Chrome or Edge on a computer or Android, Firefox on a computer, Safari on iOS 26 or later). Other browsers take up to 50 MB per file and hold 100 MB of received files at a time.
  • Files over 2 GB need PairOnce Pro on one of the two devices. Then a file can be up to 10 GB, received the same way, and the relay carries 5 GB a month.
  • When the two devices cannot reach each other directly, an encrypted relay carries the data. Each device can send and receive 200 MB a month that way, counted together; a direct connection has no monthly limit.
  • Both pages must stay open until everything has arrived: keep the phone’s screen on and the browser in front.
  • PairOnce moves things between two devices that are open at the same time. It is not cloud storage: nothing waits on a server for later.

Other ways to do it

  • A USB drive formatted as exFAT. Needs no network, and both systems read and write exFAT; any other format is read-only or unreadable on one of them.
  • File Sharing on the Mac. Turn on File Sharing, then connect from Windows with the Mac’s address; no extra software, but it takes some setup and both computers must be on the same network.
  • A cloud drive. Upload on one, download on the other; works at any distance, but needs an account and the file goes through the cloud first.
  • LocalSend. Free and open source. It works through an app on both computers, over the local network.
  • Email or a messaging app. Fine for small files; attachments are limited.

Common questions

Do the Mac and the PC need to be on the same network?

No, but the same Wi-Fi is fastest. On different networks PairOnce often still connects directly; if not, it uses an encrypted relay, which carries 200 MB a month per device.

How big can a file be?

Up to 2 GB per file when the receiving computer uses Chrome, Edge or Firefox. For a file over 50 MB, choose one of those three on the receiving side.

Is anything stored in the cloud?

No. There is no cloud storage. Files go to the other computer, directly or through a relay that only forwards encrypted data and keeps nothing, and wait in its page until you save them.

Do I need to install anything?

No. Both computers only open paironce.com; there is no account and no app.