https://codeberg.org/blast/blastqr

Hello! I’ve been working on blastQR for a couple of years now and I thought this community might find it useful. Feel free to try it and ask me anything!

blastQR is a fully open-source file transfer app and protocol that works completely offline. You can even use it in airplane mode. Data is transferred through sequences of QR codes displayed on a sender device and scanned by a receiver device’s camera. It uses RaptorQ codes so the receiver can recover the file from any sufficiently large subset of frames.

Note that although I have made use of AI as a coding assistant I do not consider this to be a vibe-coded app and I do plan to continue improving it and supporting it in the future.

See video of blastQR in action: https://github.com/user-attachments/assets/038a2567-70c8-47c8-b165-dea858d1aef3

Here are some of the key features:

  • Works fully offline: No internet, Wi-Fi, Bluetooth or servers. Your data stays offline.
  • One-to-many distribution: Share the same file with multiple devices simultaneously using a single blastQR broadcast.
  • Cross-platform: Android, iOS, macOS, Linux and Windows, plus a command-line tool that can send from a terminal, even over SSH.
  • Password encryption: You can optionally encrypt files with an auto-generated password or a custom one.
  • Media compression: The app supports lossy image compression and video transcoding for quicker transfers.
  • Multiple codes on screen: Shows multiple QR codes at once for higher speed. With 8 codes at 60 fps, transfers peak at around 1.4 MB/s.
  • Send multiple files in one go: They’re zipped into one transfer and unpacked into separate files on the receiver.
  • Sound feedback: The receiver plays a short tone when it has the whole file, and the sender stops automatically when it hears it.
  • Start scanning at any point: No need to catch every code, just keep the camera on the screen until it’s done. Blurry or missed codes don’t matter.
  • Regular QR scanner: You can also scan normal QR codes and save them.
  • Open protocol that other apps can implement
  • Built-in file manager

I’m trying to build a small community around the project so it can be improved and maintained and so it can reach more people in the future.

Downloads for all platforms can be found here: https://codeberg.org/blast/blastqr/releases/latest

  • blast@lemmy.dbzer0.comOP
    14·
    24 hours ago

    You bring up great points!

    Here are some benchmarks including videos (Note that these are best case conditions but should be achievable): https://codeberg.org/blast/blastqr#real-world-benchmarks

    Most of the testing I did with my now 7 years old Galaxy S10e. It only scans at 30FPS but it can handle 6 codes at once which is a pretty decent 420 kB/s. During testing on the iPhone 17 which can scan at 60 or 120fps I think the CPU did not become the bottleneck until around 8 codes at more than 90fps. That is something I still need to test and document more thoroughly though.

    I do use standard QR codes. By default Version 40 which can store almost 3 KB. It is configurable in the app’s settings.

    Regarding color, libcimbar (https://github.com/sz3/libcimbar) is a project that does exactly that although the speeds are not quite as high yet. Additionally, one of the cpu optimizations in blastQR (and qr scanners in general) is to drop color so that each frame that gets copied in memory is smaller. It makes a difference when you’re processing at high fps.