How Send works
Send moves a file from one browser to another using WebRTC, the same technology video-call websites use to send your camera picture directly to the person you are talking to. Instead of video, Send sends the pieces of your file.
1. Two devices meet
When you open Send, your browser makes a random 8-character code and tells Send's own small pairing service (running on Cloudflare) "a device with this code is waiting". When the other device enters the code, the pairing service passes a short introduction between them: which network addresses each one can be reached at, and the encryption key fingerprints. That is all it ever sees. It never sees file names, notes or files.
2. A direct, encrypted line opens
With that introduction, the two browsers connect to each other directly, through home routers and mobile networks, using a technique called ICE. Every WebRTC connection is encrypted with DTLS, the same family of encryption as the padlock in your address bar. Browsers do not allow an unencrypted WebRTC connection, so this can't be switched off, by us or anyone else.
As soon as the line is open, both devices disconnect from the pairing service. From then on the code is useless: nobody can use it to join.
3. You choose what to accept
When one side drops a file, the other side first receives only its name, type and size, and taps Accept or Decline. Only after Accept does the file start to move, in small pieces, with a progress bar, speed and time left on both screens. Files that can run programs (like .exe, .apk or .bat) carry a warning.
4. The file is saved on the receiving device
On phones and most browsers, the received file is kept in the page until you tap Save; then it goes to your Downloads like any other download. In Chrome and Edge on a computer, files larger than 200 MB are written straight to the place you choose, so even very large files don't fill memory.
What if the devices can't connect?
Most home Wi-Fi and mobile networks allow direct connections. A few strict office, school or public networks block them. If that happens, Send says so after a short wait: switch one device to mobile data or another Wi-Fi and get a new code.
What Send does not do
- It does not store files, for later or at all. Close the page and nothing is left.
- It does not need an account, email or phone number.
- It does not compress or change your files.
Want the safety details? Read how Send keeps your files private.