In-browser barcode and QR code reader. Nothing leaves your device — the decoder is gozxing (Go port of ZXing) compiled to WebAssembly. Your camera feed is processed locally frame-by-frame, never uploaded.

Scanner

tap Start, then tap on a barcode

loading wasm…

Tap the video to scan a specific region. Auto-scan runs in the background.

Supported formats

Type	Formats
2D	QR Code
1D (product)	UPC-A, UPC-E, EAN-8, EAN-13
1D (industrial)	Code 128, Code 39, ITF

How it works

Camera — the browser's getUserMedia API opens the rear camera.
Frame capture — every ~250 ms, the current video frame is drawn to an offscreen canvas and the RGBA pixel data is extracted.
WASM decode — the pixel buffer is copied into the Go WASM module, which constructs a BinaryBitmap and runs each reader (QR, EAN/UPC, Code 128, Code 39, ITF) until one matches.
Tap-to-scan — tapping the video crops a 40%-of-frame region around the tap point and decodes only that, reducing noise and speeding up detection.
Result — decoded text is displayed and auto-copied to clipboard.

Privacy

Zero network requests after the page loads. The WASM binary and wasm_exec.js are static files served from this domain. Camera frames never leave the browser tab. There is no server-side component — the Go HTTP server in the source repo is only for local development.

Self-host / build from source

Source: git.nixc.us/colin/wasm-qr

git clone https://git.nixc.us/colin/wasm-qr.git
cd wasm-qr
make run

The Makefile compiles the WASM binary, copies wasm_exec.js from your Go installation, and starts an HTTPS server with a self-signed cert on :8443.

Limitations

gozxing is less robust than native ZXing — works best with good lighting and a steady hand.
iOS Safari and Chrome on mobile require HTTPS for camera access (this page is served over HTTPS).
WASM binary is ~4 MB (first load only, then cached).