Files that travel as music.

Send a file with sound

Tone Transfer moves a file or a short message between two nearby devices using nothing but a speaker and a microphone. Open the page on both, pick what you want to send, and one device plays a few seconds of music. The other one hears it and the file arrives. There is no pairing screen, no account, no QR code to line up, and nothing to install on either side.

It is useful exactly where the normal options get awkward — handing a photo to someone on a different platform, moving a file to a borrowed laptop, getting a document off a locked-down machine where you cannot install anything, or sharing with a room full of people at once, since anyone within earshot receives the same melody. Sending data over sound is an old idea; doing it in a browser tab with no setup is the part that makes it practical.

How it works

1. Pick a file or type a message. It is encrypted in your browser with AES-256-GCM before anything leaves the tab, and given a four-character transfer code.
2. Play the melody. Those four characters are encoded as a short run of notes on a pentatonic scale, bracketed by start and end phrases so the receiver knows where the code begins and ends.
3. The other device listens. Its microphone picks out the notes, rebuilds the code, fetches the encrypted payload, and decrypts it locally. Files save to disk; messages appear with a copy button.

Read the full walkthrough for the note encoding, the error checking, and what to do when the receiver does not hear anything.

What stays on your device

Worth being precise about, because “sent as sound” sounds like more than it is:

• Encryption happens in your browser, before anything is sent — AES-256-GCM via the Web Crypto API.
• Your microphone audio is analysed on your device and never recorded, stored, or uploaded.
• The melody carries only the four-character code. Never your file, never your key.
• The encrypted payload is held as a private object with no public URL — it cannot be listed or browsed.
• Downloads are one-time. Receiving a transfer deletes it.
• Anything unclaimed expires after ten minutes.
• No account, no pairing, no QR code, no app install.

The encrypted payload does pass through a relay so the two devices do not have to negotiate a direct connection, and the relay holds the decryption key for those ten minutes. The privacy model spells out exactly what is stored and for how long.

What you need

A modern browser on both devices, with JavaScript enabled. The sending device needs working speaker output; the receiving device needs microphone permission. Both need an internet connection. Keep the devices close enough that one can clearly hear the other — a quiet room helps, and so does turning the volume up. Older audio codecs are still available on the legacy engines page if you need to match a device that struggles with the default one.