Privacyhttps://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
Is this the future version of holding two phones together to transmit files via infrared?
What was your testing environment?
First thing I thought about is how well smartphone can handle it. After fps mismatch that you contributed on, there is also cameras matrix' resolution, probable obstacles and image distortion.
After that, I'm interested in how able a smartphone to scan a max res QR like in the OP gif. Or eight of them. 25 times a second, with a CPU overhead of error correction algorhitm. I know modern phones are beasts, but basic apps I used struggled with QRs that vere too busy, and even if not, they still took a second before popping up a link.
Btw, do you use standard QR by specs, or a custom 2d encoding method? I don't see rectangular orientation marks on your images, so it's something new. Since you are not sticking to QRs, have you thought of using colors, since your usecase is capturing color displays?
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.
Since you advertise it for Obtainium, would you mind adding the key for verification with AppVerifier? I didn't find it in the readme and release.
Thank you for the suggestion!
dev.blastapps.blastqr 60:E3:A6:C0:63:1D:C3:A0:0C:78:E4:C9:E4:89:B3:03:4F:A9:7D:49:D0:B9:3E:CF:56:B2:33:A8:C3:DD:F6:83
it's been added to the readme as well.
Dope, thank you very much!
Two more questions: Is there a way to set 8 codes for sending in the flatpak version, or is that limited to 6? Any idea why a pixel 8 pro on graphene wouldn't allow 120/240 fps receiving? Highest I've been able to choose and test is 60fps. was thinking that it may be the resolution cap, but an iPhone comparison ran at 240fps with the same res (I think).
The app is limited to 6 right now but I'll work on increasing it! The CLI tool does allows up to 12. Make sure you use Ghostty or Kitty for high frame rates if you do decide to try it.
A lot of phones cap the camera preview at 30fps actually so 60fps is quite good already. From the devices I tested only the iPhone let me select 60,120,240. You can see some benchmarks here: https://codeberg.org/blast/blastqr#real-world-benchmarks I don't think you are missing out on performance if you can scan at 60fps. I recall at 120 the cpu was starting to be the bottleneck but I'll have to do some more testing to confirm.
Yeah, thanks for the input. i did realise that the iPhone too performs best at 60FPS actually(anecdotally).
This is truly a cool project. thanks for your work!
Isn't app verifier a dead project?
Nice, but what is the use case?
Some of the use cases I thought about:
- Regular file transfers: It works well as long as the files are not too big. I use it often between my phone and laptop.
- Sensitive information: You can transfer files without relying on cloud services or network infrastructure. There's a password encryption feature for that. If you don't enable that someone could decode the information from the QR codes.
- Broadcast on a large screen so multiple devices can receive data without requiring an internet connection during internet outage/government internet crackdown.
- Air-gapped systems: Transfer files to and from devices that are not connected to a network.
Hopefully people will find new and interesting use cases for it too.
lemme guess it's vibecoded
%99.99 of all new open source projects are vibecoded unfortunately.
Not using AI for writing code in late 2026 makes sense only for learning purposes. To not “vibecode” is unjustified self inflicted pain otherwise. Good use of AI with latest models generate better and more maintainable code. I do not see how that is unfortunate. Bad practices and old bad models were indeed an issue. Now things have changed.
Yeah but that's no fun. Why would I use a project that isn't any fun?
Cope
lmao
Snow Crash here we come!
J/k, cool idea.
Note that although I have made use of AI as a coding assistant this is not a vibe-coded app
Can you elaborate more on how AI was used?
For context, I'm a software developer with around 15 years of experience. Most of it writing Android and iOS apps in Java, Kotlin, Swift and lately Dart (Flutter) + Rust which is what this project is written in.
Although I did start the project from scratch I have lately been using Claude Code as a coding assistant. I write code myself but I also let it write or refactor parts of it. The CLI tool is the part that Claude has mostly written from scratch because it's not something I had experience in writing before. That being said I also review all the code that Claude writes.
Thanks for asking! there's also some disclosure about this in the readme file
Thanks for being honest and open about it
The CLI tool is the part that Claude has mostly written from scratch because it's not something I had experience in writing before.
This seems like the perfect opportunity to learn something new in my opinion, CLIs aren’t difficult to make. And you may want to consider moving to GitHub because of Codeberg’s ToS.
I totally agree and I'm very open to welcome anyone who wants to rewrite that part or I might go for it myself in the future. The reason I went for it is that I really wanted to be able to use the CLI tool right away and the AI produced a good result so I left it in the project for now.
About Codeberg I did read their blog post and I didn't think my project falls into any of the cases they mention: ::: spoiler spoiler Projects that are created by LLM "agents" in autonomous ways Projects written and maintained with heavy use of LLMs Projects where the amount of resources (e.g. storage, CI/CD) is significantly larger than what the involved amount of people could have created by hand Projects heavily tied to the LLM ecosystem, e.g. LLM-written tools to ease LLM usage Users sending LLM contributions in violation of project's custom policies :::
If they ever consider it infringing their ToS I could move it to GitHub where there's already a mirror of the repo.
Now use steganography to hide files in the qr code images. Maybe even make those hidden file qr codes.
Super cool! I could totally see this being an integral plot point in a show or movie. Crowds of people suddenly aiming their phones at the screens in Times Square to get the latest elicit data dump or some such 😎
Thanks for all the hard work, I can't wait to play around with it!
*illicit
Interesting, though what if the receiver fails to scan the codes quicly enough?
The cool part is that codes are generated indefinitely so basically you can keep scanning until you receive the data. You don't need to capture every frame or scan in any particular order.
This is made possible by raptorQ (https://github.com/cberner/raptorq) the fountain code encoding used by blastqr.
Feel free to try it out!
How many pictures does it show per second? And do I understand that right, it cycles through the data until it hears the sound? I assume that makes sending large files difficult, since it has to wrap around all the data, right?
You can tweak the FPS from the send page UI. it's set to 25 fps by default for broader compatibility (most devices capture at 30fps) but if you have a more powerful device they can capture at 60 or 120fps and you can adjust the sender accordingly. Each frame carries around 3kB of data per frame (with the default settings) so at 25fps that's 75kB/s. You can multiply the speed by showing more than one code. So two codes would give you 150kB/s
The completion tone is optional. It basically just tells the sender that it can stop and t's more for convenience. I want to expand it in the future so the receiver tells the sender what FPS to send at through sound tones.
Regarding large files it can take a long time yes! The app includes lossy compression turned on by default when you send pictures or videos (similar to what all chat apps do) so it can send those quite fast. With default settings and showing 2 codes it can send 5 pictures in around 10 seconds for example or a 2MB video in the same time.
That's a clever approach, thanks for the explanation
Reminds me of CimBar, but yours seems to be way faster! Maybe i'll try it, for the fun of it 👍
Seems easier to just grab a USB flash drive.
If you happen to have one handy
Indeed but nowhere as fun ;)
it is most useful when you don't want to connect anything or need to broadcast data to multiple devices simultaneously. For example transmitting info to a bunch of phones during a digital blackout where the government has cut off internet. Also useful for air-gapped systems!
Wouldn’t any security camera potentially be able to steal the information by inputting the QR codes though? It’s not truly airgapped when someone can view or also be able to see the information that’s being sent.
Yes, absolutely! anyone who can capture the QR codes could reconstruct the data. That's why blastQR also lets you password encrypt any transfer. It depends on your usecase. You might not care if you're already intentionally publicly broadcasting to multiple devices.
Air-gapping refers to network isolation not necessarily confidentiality. It means you can transfer data to and from devices that are completely disconnected from any network.
Air-gapping refers to network isolation not necessarily confidentiality. It means you can transfer data to and from devices that are completely disconnected from any network.
Which also includes the information not being seeing or taking, it’s kinda one of the main points. Your program is not even remotely similar to being airgapped and you shouldn’t be saying or even implying that feature. Especially in a comm like this. Why would you want to transfer without being connected to a network or a “physical” connection? For privacy and security, and lots of airgapped system still utilize networks and lines.
As explained in the readme you should enable password encryption when transferring sensitive data. I'm not claiming the program itself is air-gapped, just that transferring files between air-gapped systems is a legitimate use case.
