Summary
- Beam files from PC to Android by pointing your phone at a flashing color barcode—no network required.
- Reed‑Solomon + fountain codes correct errors and reassemble files (up to 33MB); claimed speeds ≈850KB/s.
- Sideload the Android app, open cimbar.org on your PC, upload a file, then scan the animated screen to save.
There’s no shortage of methods for transferring files from a computer to a phone. Wi-Fi, Bluetooth, SD cards, USB drives, etc. What if you could beam a file from your PC to your Android phone just by pointing your camera at an image?
You probably know QR codes—those black-and-white squares that are great for sending links to a restaurant menu to your phone. But try to send something more complex using a standard QR code, and it doesn’t work so well. Libcimbar is a clever web app and Android app that uses a specialized two-dimensional barcode format called Color Icon Matrix Barcodes (Cimbar), and it turns your entire screen into a data transmitter.
Sending files through a scannable code is cool enough, but here’s the wild part: you don’t even need an internet connection. Your computer screen flashes a constantly changing, high-density pattern of colored blocks, and the app on your phone uses the camera to capture the animation. After a few seconds of scanning the pattern, the app asks where you’d like to save the file, and it’s put together on your phone. The developers claim this setup can hit speeds of up to 850KB per second, which isn’t going to dethrone fiber, but for being wireless and offline, it’s impressive.
There are some obvious issues with optical transfers—like the camera shaking or screen glare—and they’ve tried to address them. This project is built with “Reed-Solomon error correction” codes. Even if your camera misses some frames or there’s a smudge on your lens, the system can self-correct and recover the data.
For larger payloads, it uses something called “fountain codes.” These let them split a file up to 33MB into a massive series of animated frames. As long as you capture enough of the unique frames, the system can reconstruct the original file perfectly, even if some parts are corrupted or out of sequence.
To use the tool, first sideload the APK on your Android phone from the GitHub page. Then simply go to cimbar.org in a browser on your computer and upload a file from the sidebar menu. Next, open the app on your phone and line up the viewfinder for a few seconds. Once it’s recognized, you can choose a folder for the file, and it will be transferred. Super cool.