CarbonStamp

Estimates the carbon footprint of every webpage you visit

CarbonStamp estimates the carbon footprint of every webpage you visit — automatically, privately, and grounded in real grid data. Every byte of every page costs energy. CarbonStamp combines transferred page weight, the carbon intensity of the server's electricity grid, and whether the host is on the Green Web Foundation registry to give each page a letter grade from A+ to F, just like websitecarbon.com — but for every page you actually visit, without opening DevTools. ⚠️ Setup required — bring your own API keys CarbonStamp needs two free API keys before it can work. This is intentional: it keeps the extension free for everyone and keeps your browsing data completely private — your keys, your account, no shared backend. You'll need to sign up for two free accounts (takes about 2 minutes): ip2location.io — free tier covers 30,000 lookups per month https://www.ip2location.io/ Electricity Maps — free tier for personal/research use https://api.electricitymap.org/ The third data source — Green Web Foundation — requires no key. After installing, open the extension popup and paste your keys into the setup screen. They're stored locally in your browser and never sent anywhere except the APIs themselves. What it does 📊 Per-page carbon score Total transferred page weight (KB / MB) Estimated energy used (kWh) and CO₂ produced (grams) A+ to F letter grade matching the websitecarbon.com methodology Real-time grid carbon intensity by hosting country (Norway ≈ 30g CO₂/kWh, Poland ≈ 700g CO₂/kWh) Green hosting check via the Green Web Foundation registry 🏆 Your browsing dashboard Daily, weekly, and monthly cumulative footprint Top 10 heaviest sites by average carbon per visit (D3.js chart) Annual estimate with relatable comparisons: km driven, short-haul flights, meals of beef 🎨 Colour-coded badge Green for A+/A, amber for B/C, red for D/F Updates automatically on every page load — passive carbon awareness 📤 Exportable summary Shareable browsing footprint report copied to clipboard How it works CarbonStamp uses the browser's built-in PerformanceResourceTiming API to measure transferred bytes when each page finishes loading. It then: Looks up the hosting country from the domain (ip2location.io, cached 24h) Fetches the current grid carbon intensity (Electricity Maps, cached 1h) Checks the Green Web Foundation registry for green hosting (cached 7d) Applies the websitecarbon.com open methodology to estimate CO₂ All caching is local. All data stays in your browser. Privacy — your browsing stays yours 🔒 No backend server. No account. No telemetry. No tracking. 🔒 No data leaves your browser except API calls to the three providers (domain only — never full URLs or page content). 🔒 API keys are yours. Stored in chrome.storage.local, never transmitted to anyone except the API providers. 🔒 Local-only storage. Page history auto-deletes after 90 days. See the full privacy policy: [included with submission] Permissions explained CarbonStamp asks for the minimum permissions needed: storage — to store your page history and API keys locally alarms — to run the daily cleanup job that prunes data older than 90 days activeTab — to read the URL of the page you're currently looking at (only when you open the popup) host permissions for api.ip2location.io, api.electricitymap.org, api.thegreenwebfoundation.org — the three APIs that power the carbon estimate CarbonStamp does NOT request tabs, history, webRequest, or any permission that would let it see your browsing across other tabs. Built by Sola Samuel