A developer going by the name bashalarmistalt has built an experimental file-transfer system called Decimen Optical Transfer that sends data between smartphones using a rapidly cycling sequence of QR codes.
The system requires no dedicated app, Wi-Fi connection, Bluetooth, or device pairing. Users open a web page in a browser and grant camera access. One phone displays a continuous stream of QR codes on its screen while the second phone’s camera reads them in sequence. An algorithm then reassembles the blocks into the original file.
Central to the system are so-called fountain codes, which allow it to recover a complete dataset even when some frames are missed by the camera.
In testing, the developer reached transfer speeds of around 128 KB/s when holding the phones by hand, rising to between 186 and 190 KB/s when the devices were held completely still.
The project is released under an MIT licence and remains a proof of concept. Decimen Optical Transfer is slower than Wi-Fi, Bluetooth, and even NFC, but the developer points to a potential niche in situations where wireless interfaces are unavailable, disabled, or undesirable.
