Decimen Optical Transfer — Transfer files between devices using only a screen and camera, no network needed.
Analyzed by Sai Pavan Gopularam · Utility · Offline Transfer · View on GitHub
- Stars: 6692
- Forks: 809
- Commits last 30 days: 13
- Health: Active (13 commits this month)
- Language: TypeScript
- License: AGPL-3.0
What It Is
Imagine sending a file from your laptop to your phone by just showing a QR code on your screen and taking a picture with your phone's camera. Decimen Optical Transfer does exactly this: it converts files into a stream of animated QR codes, letting another device 'read' the data through its camera, without any network connection.
This solves the problem of transferring data when networks are unavailable, unreliable, or untrusted. It eliminates the need for cables, Bluetooth pairing, or cloud services, offering a truly air-gapped and permission-free way to move small files, up to 64 MB, across devices.
License Verdict
AGPL-3.0-or-later — Use with Caution for Commercial SaaS — Commercial Use Restricted • Copyleft Applies to Networked Services
The AGPL-3.0 license means if you modify this software and offer it as a service over a network (e.g., a SaaS product), you must make your modified source code available to your users. This significantly limits commercial SaaS applications unless you want to open-source your entire product. For internal use or desktop applications, it's less restrictive.
How to Use It
To get started, clone the repository, install Node.js dependencies, and run the development server. You'll then open the sender URL on one device and the network URL on another, typically a phone, to begin transferring files.
Prerequisites:
- Node.js
- npm
Estimated setup time: 10 minutes.
npm install
npm run dev
# Open https://localhost:5173/send/ on sender
# Open the 'Network' URL printed in terminal on receiverWhat I'd Build With This
Air-Gapped Data Bridge for Sensitive Environments (micro-saas)
A specialized web app (deployed locally or on an intranet) for transferring configuration files, small documents, or secure keys between air-gapped systems and internet-connected devices. Target users are cybersecurity professionals, government contractors, or industrial control system operators who need to move data without USB drives or network connections. Market this through niche forums and direct outreach to security firms.
Effort: 3 Weeks Build Time · Target: Cybersecurity Professionals, Industrial Control Systems · Pricing: $99/mo per team license
Offline Content Distribution for Public Displays (saas)
A service for businesses to update digital signage, public information kiosks, or classroom displays without needing a direct network connection to each screen. Content managers upload media, generate a QR stream, and then use a phone to 'broadcast' it to the display's camera. This would be an on-premise solution for larger organizations, managing content centrally and deploying locally. Pricing could be based on the number of managed displays or content updates.
Effort: 2 Months Build Time · Target: Retailers, Museums, Schools, Digital Signage Providers · Pricing: $299/mo per organization
Secure Offline Firmware Updates for IoT Devices (enterprise)
Develop a specialized solution for manufacturing or critical infrastructure companies to push firmware updates to IoT devices that are air-gapped or have unreliable network access. The update package is streamed via a screen-to-camera interface directly to the device's camera, ensuring physical proximity and preventing remote exploits. This requires custom hardware on the device side to interpret the optical data. Revenue comes from custom development and licensing for large deployments.
Effort: 6 Months Build Time · Target: IoT Device Manufacturers, Critical Infrastructure, Defense Contractors · Pricing: $50,000+ per custom integration
Sai Pavan Gopularam's Take
This project is a fascinating demonstration of how to bypass network infrastructure entirely for data transfer. The AGPL license makes traditional SaaS tricky, but it's perfect for air-gapped systems or secure on-premise deployments. I estimate a niche tool for secure configuration transfer could fetch $5k-$10k/month from government contractors.
Watch Out For
- AGPL License: The AGPL-3.0 license means that if you modify and distribute this software, or offer it as a networked service, you must make your modified source code available. This severely limits traditional SaaS business models.
- No Encryption: The transfer is not encrypted; whatever is on the sending screen is readable by any camera. This means it's unsuitable for confidential data unless operating in a physically secure environment.
- Speed Limitations: While impressive for an optical transfer, the speed is limited (around 400 KB/s max). This makes it impractical for very large files (e.g., gigabyte videos) and best suited for smaller documents or images.
- File Size Limit: The current implementation has a 64 MB file size limit, which needs to be considered for use cases involving larger media or datasets.
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