Air-Gapped Communication

Send datathrough sound.

Transfer messages between nearby devices using only speakers and microphones — audible or ultrasonic. Save the signal as an audio file, or fall back to a QR code. No internet, no Bluetooth, no cable.

NO NETWORKS ACOUSTIC TRANSFER QR FALLBACK

How it works

Everything runs inside your browser. Nothing is uploaded, and nothing is stored on any server.

STEP 1Type your messageUp to 720 bytes. Longer messages are split into parts automatically, and every part carries Reed-Solomon error correction.

STEP 2Play it or save itTransmit through the speaker right away, or export a .wav file and send it on WhatsApp, email or Messenger.

STEP 3Decode on the other sideThe receiver listens with the microphone, or simply drops the audio file in — band and speed are detected automatically, and damaged symbols are repaired.

OPTIONALSecret key & QRAdd a key so only the right person can read the message, or show a QR code when the room is too noisy for sound.

BUILT INMade for real roomsEach part measures the speaker and microphone response, corrects clock drift between devices, and carries Reed-Solomon error correction, so a few damaged tones are repaired instead of losing the message.

IF IT FAILSWhat to changeMove the devices closer, raise the volume, switch both to Reliable or Maximum speed, or send the message twice. An echoey room hurts far more than background noise.

Transmit data

Message

0 bytes~0.0s transmission

Secret key (optional)

Band

Speed

Send

Volume

Tip: keep both devices 10–50 cm apart, raise the volume, and make sure the receiver is already listening before you press transmit. In a big or echoey room use Reliable or Maximum speed and move the devices closer.
Sharing the .wav: attaching it as a file / document is the safest — compressed re-encodes usually still decode, but a document is always exact.

Receive data

Ready to listen

Keep devices close together and ensure volume is up.

Or decode an audio file

Choose or drop an audio file A file received on WhatsApp, email or Messenger — decoded offline, band and speed detected automatically.

Secret key (optional)

Band

Speed

Live microphone: band and speed must match the sender, and microphone access requires HTTPS. Hold the two devices close and keep them still while the tone plays.
Audio file: band and speed are detected automatically — you only need the secret key, if one was used.