--- title: 'CarbonGrader - test how sustainable your website is' url: 'https://byintention.co/insights/carbongrader-test-sustainable-website' markdown: 'https://byintention.co/insights/carbongrader-test-sustainable-website.md' date: '2026-11-05' description: "We built a lightweight web app using open source and free libraries, inspired by EcoGrader.\_ Click to learn more and try out the free tool!" --- [Blog](https://byintention.co/insights) # CarbonGrader - test how sustainable your website is 5 November 2026 ![screenshot of carbongrader with text 'how green is your site'](https://byintention.co/user/media/blogs/carbon-grader-blog.webp) We built a lightweight web app to test how sustainable a web page is. It uses open source and free libraries, and is inspired by EcoGrader. Use our free tool to test your site, get an easy to understand score and a list of the most important fixes to make. - Estimate the carbon output of a page - Test performance - load time, page size etc - Check if your hosting provider uses green energy [Try CarbonGrader](https://grader.byintention.co/) ## Why use CarbonGrader? ### Speed A sustainable site is also a fast site, which is good for your visitors. If a site takes too long to load your visitors might give up and go elsewhere - losing you that sale or enquiry. ### Search Engines Search engines like Google also love fast sites, and fast page load times can contribute to better search engine rankings. ## How CarbonGrader works The carbon output of a page is estimated by [CO2.js](https://www.thegreenwebfoundation.org/co2js/) (Apache-2.0) and Greencheck to see if the hosting provider uses sustainable energy or not. Both these are from the [Green Web Foundation.](https://www.thegreenwebfoundation.org/green-web-datasets/) Performance is tested using the [Google PageSpeed Insights](https://developers.google.com/speed/docs/insights/v5/about) API and simplified - full results for a page can be seen from [Pagespeed Insights](https://pagespeed.web.dev/) The app is coded in Javascript with the interface built using the [UIKit](https://getuikit.com/) framework (MIT), plus a sprinkling of custom CSS. --- ## Navigation - Parent: [Blog](https://byintention.co/insights.md) - Next: [PHP Critical Update - October 26](https://byintention.co/insights/php-critical-update-october-26.md)