A proof-of-concept system named Decimen Optical Transfer has been developed to transfer files between phones by streaming QR codes from one device's screen to another device's camera.
The project was created by a developer known as bashalarmistalt on GitHub and Alstroph on Reddit. The developer used Claude Code to build the Decimen Optical Transfer cached web app.
A phone-to-phone file transfer option without requiring the phones to be on the same network
The system runs in a browser on smartphones using their cameras and requires no dedicated app, no same-network connection, and no device pairing. It requires no permissions beyond camera access.
Technical mechanism and speed
To facilitate the transfer, QR codes are generated in the browser and refreshed at up to 60 frames per second. The sender displays these rapidly changing QR codes, which the receiver's camera reads to rebuild the file. Each streamed QR code frame carries a 20-byte self-describing header containing the session ID, sequence number, block count/size, file length, and a hash.
The system utilizes a 'fountain code' error-tolerant coding technique, which ensures that missed or unreadable QR frames do not interrupt the transfer process.
Maximum claimed transfer speed
In handheld tests using an iPhone, the developer achieved a transfer speed of approximately 128 KB/s. When both the sender and receiver devices were kept completely stationary, the speed reached about 186 KB/s.
The developer's GitHub information indicates that transfers can run at up to 190 KB/s.
Availability and context
Decimen Optical Transfer is presented as an alternative for scenarios where devices cannot join the same network or where there is no internet connection. The developer acknowledged that similar projects have been performed previously but stated this concept was developed independently.
The project is currently at the proof-of-concept stage and is released under the open-source MIT license.
