Built this for the day the internet and every normal way of moving a file stop being an option. Two webcams, QR codes flashing between them, nothing else. The protocol handles reliability with a sliding-window ACK/retry scheme, and does ECDH key exchange with fingerprint verification since a QR code on screen is about as public as a channel gets. Throughput lands around 20 KB/s, slow, but well, it's the only option when you need it. Live demo: https://stare.asilentpond.com Devlog on how it was built: https://youtu.be/q3fQZ-ZXqow