QR Bridge - Offline Transfer

Move a file from one phone to another using nothing but a screen and a camera.

QR Bridge turns your file into a stream of QR codes. The sending phone flashes them, the receiving phone reads them with its camera and rebuilds the file. That is the entire mechanism — no Wi-Fi, no Bluetooth, no cable, no pairing, no account, and no server anywhere in the path.

★ How it works

1. Prop both phones up facing each other, 10-20 cm apart.
2. One picks a file and taps Send. The other taps Receive and aims.
3. When the receiving phone turns green, hit Stop. You are the acknowledgement — that is the whole protocol.

★ When this is the right tool

• Air-gapped machines and secure sites where radios are not allowed
• A phone with no SIM, no Wi-Fi, or no matching cable
• Moving something between Android and iPhone without signing into anything
• Any document you would rather not hand to a cloud service on its way across a table

★ Built around the camera

QR is a 10-25 KB/s channel and no amount of protocol tuning changes that, so every control exists to help you find the fastest setup your two phones can actually manage.

• Live capture rate with a plain verdict — GOOD, WEAK or NONE — so you can see at a glance whether to move the phones closer or drop the density
• Shrink a photo before sending and watch a two-minute transfer become a fifteen-second one. The app shows you the time saved, not just the bytes
• One or two codes on screen. Two stacked squares cover about 1.9x the area of one while each module shrinks only 2%. Three would be worse on both counts, so it is never offered
• Density, slot rate and aim time are all adjustable, because faster is not automatically better — a camera samples about 30 times a second and tears anything that flips mid-readout
• Fountain coding, so frames can arrive out of order and missed ones simply do not matter
• SHA-256 verification on arrival, so you know what landed is exactly what was sent

★ There is no network code in this app

Not a figure of speech. QR Bridge requests no INTERNET permission and ships with no HTTP client, no analytics and no crash reporting. The camera is used for one thing — reading the codes in front of it — and the feed is never recorded or saved. Received files land in the app's own folder and go nowhere until you share them yourself.

Any file type. The practical limit is patience rather than bytes: this is built for documents, photos, keys and configuration files rather than films.