Barcode Scanner

Read barcodes and QR codes without downloading an app. This runs entirely in your browser sandbox — the decoder is gozxing (Go port of ZXing) compiled to WebAssembly. No installs, no permissions beyond camera access, nothing that can inadvertently load dangerous software onto your device.

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

TypeFormats
2DQR Code
1D (product)UPC-A, UPC-E, EAN-8, EAN-13
1D (industrial)Code 128, Code 39, ITF

How it works

  1. Camera — the browser's getUserMedia API opens the rear camera.
  2. Frame capture — every ~250 ms, the current video frame is drawn to an offscreen canvas and the RGBA pixel data is extracted.
  3. 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.
  4. 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.
  5. Result — decoded text is displayed and auto-copied to clipboard.

Privacy & safety

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.

Because everything runs in the browser sandbox, you avoid the risk of installing barcode apps that request broad permissions or load unwanted software. For simple scans, no app download needed.

Self-host / build from source

The source is a small Go project. To build and run locally:

# requires Go 1.21+
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).