Chook Check

Browser extension for tracking Australian supermarket prices, detecting personalised pricing, and empowering consumers through community data.

"Just doing a quick chook check before heading to Woolies."

Chook Check passively records prices as you browse Woolworths and Coles, stores them locally in your browser, and — if you choose to opt in — contributes them to a community dataset that helps everyone spot pricing inconsistencies, sale patterns, and personalised pricing.

Status

In active development. Not yet listed on the Chrome Web Store or Firefox Add-ons. See Manual installation below to try it.

Privacy at a glance

• Default: all data stays on your device. Nothing is sent anywhere.
• Opt-in contribution: if you turn it on, you choose exactly which optional context to share alongside the price data. Each toggle is independent.
• No accounts, no IPs: the API never logs IPs against observations, and there's no signup.
• Open source on both ends: this extension (MIT) and the community API (AGPL-3.0).

Full details in PRIVACY.md.

Manual installation

Chrome / Edge / Brave

1. npm install && npm run build
2. Open chrome://extensions, enable Developer mode
3. Click Load unpacked and select .output/chrome-mv3

Firefox

1. npm install && npm run build:firefox
2. Open about:debugging#/runtime/this-firefox
3. Click Load Temporary Add-on and select .output/firefox-mv2/manifest.json

Development

Requires Node 20+ and npm.

npm install
npm run dev              # Chrome dev with HMR
npm run dev:firefox      # Firefox dev
npm test                 # Vitest in watch mode
npm run test:run         # one-shot
npm run lint
npm run format

Build commands:

npm run build            # Chrome production build
npm run build:firefox
npm run zip              # zipped artifact for store submission
npm run zip:firefox

Architecture

• WXT extension framework, Manifest V3 (Chrome) / V2 (Firefox)
• React 19, Chart.js for the dashboard, hand-rolled SVG sparkline for the overlay
• Dexie.js wrapping IndexedDB for local storage
• All network I/O goes through the background service worker — content scripts and UI never fetch directly

Scrapers use a layered fallback: JSON-LD → JS hydration state (__NEXT_DATA__ etc.) → DOM selectors.

Testing

Vitest with happy-dom and fake-indexeddb. UI tests use @testing-library/react. Run npm run test:run.

Backend

The community API lives at https://github.com/Nevenit/chook-check-api. AGPL-3.0 — anyone running a modified service must publish their source.

Contributing

See CONTRIBUTING.md. Bug reports and PRs welcome.

License

MIT.