QR Secure Share

Offline file transfer and QR code generation. Share files between devices using animated QR codes with no internet required.

Demo: qrsecure.kuvi.dev

Features

Text QR Generator

• Generate QR codes from text or URLs

Offline File Transfer

• Transfer files using QR codes only - no internet, servers, or third-party services
• Fountain codes (LT codes) for robust large file transfers with error correction
• Sequential QR mode for simpler transfers
• CRC32 checksums for data integrity verification

QR Scanner

• Camera-based scanning with rxing-reader WASM
• Image upload support

Tech Stack

• Frontend: React 19 + TypeScript + Vite
• Styling: Tailwind CSS + Radix UI
• QR Scanning: @andrewtheguy/rxing-wasm from rxing-reader
• QR Generation: @andrewtheguy/fast-qr-wasm from fast_qr
• Binary QR Transport: Fountain transfer worker path only (raw byte mode)
• Fountain Codes: Custom Rust/WASM implementation (architecture docs)

Prerequisites

• Bun (the version in packageManager in package.json)
• rustup; wasm/fountain/rust-toolchain.toml pins the toolchain and the wasm32-unknown-unknown target, and wasm-pack comes from the devDependencies

Installation

# Clone and install
git clone <repository-url>
cd qrcodesecureshare
bun install

# Build the fountain WASM module (once, and after every change under wasm/)
bun run build:wasm

# Development
bun run dev

# Production build (builds the WASM module first)
bun run build

Usage

Generate QR Code

1. Go to "Generate QR Code" tab
2. Enter text or URL
3. Download or share the QR code

Scan QR Code

1. Go to "Scan QR" tab
2. Use camera or upload an image
3. Scanned data is displayed and can be copied

Send File (Offline Transfer)

1. Go to "Send File" tab
2. Select a file to transfer
3. Choose transfer mode (Fountain Code recommended for large files)
4. Display animated QR codes for receiver to scan

Receive File

1. Go to "Send File" > "Receive a file"
2. Scan the metadata QR code from sender
3. Continue scanning animated QR codes until transfer completes
4. Download the reconstructed file

Project Structure

src/
├── components/
│   ├── GenerateQR.tsx      # Text/URL QR generator
│   ├── Scan.tsx            # QR scanner (camera/upload)
│   ├── OfflineTransfer.tsx # File transfer workflow
│   ├── fountain_qr/        # Fountain code transfer UI
│   └── ui/                 # Shared UI components (shadcn)
├── utils/                  # WASM bindings and helpers
└── workers/                # Web Workers (QR scanning, decoding)

wasm/
└── fountain/               # LT fountain codes implementation (Rust → WASM)

Performance

• QR decoding runs in a Web Worker that reads one camera frame at a time and skips to the newest frame when it frees up.
• The file-transfer receiver offers every new camera frame; the other scanners read at most 8 to 10 frames per second.
• Phones ask the camera for a lower resolution while receiving a file.

Planned work is in docs/roadmap.md.

Security

• Offline by design: No servers or internet required for file transfers
• Local processing: All QR operations happen in-browser via WebWorkers
• No intermediaries: Data stays on participating devices only
• Integrity checks: CRC32 checksums verify transfer completeness

Development

# Run development server
bun run dev

# Rust tests and clippy for wasm/fountain
bun run test
bun run clippy

# Lint (Biome) and type-check
bun run lint
bunx tsc -b

# Format and apply safe fixes
bun run format

# Build WASM only
bun run build:wasm

The QR reader WASM is built and published from andrewtheguy/rxing-reader; this app consumes it as the pinned package @andrewtheguy/rxing-wasm. The QR generator WASM is built and published from andrewtheguy/fast_qr; this app consumes it as the pinned package @andrewtheguy/fast-qr-wasm. Both are pulled in as GitHub release tarball URLs declared in package.json; to move to a new release, run bun add <release tarball URL>. bun run build:wasm builds only the in-repo wasm/fountain crate.

Deployment

# Build for production
bun run build

# Preview build locally
bun run preview

# Deploy dist/ folder to any static hosting

Cloudflare Pages

• Build command bun run build:cloud, output directory dist, root directory /. Set BUN_VERSION to the version in packageManager in package.json.
• cloud_build.sh installs rustup with no default toolchain, runs rustup toolchain install in wasm/fountain to get the toolchain and target its rust-toolchain.toml pins, then runs bun run build.
• wasm-pack downloads its binary in a postinstall script, which Bun runs only because package.json lists it in trustedDependencies.

License

MIT License - see LICENSE file for details.