Welcome to The Green Web Foundation's Documentation Site

What you'll find here

This site is a collection of documentation for the open source libraries maintained by The Green Web Foundation. Here you will find tutorials, guides, and explainers to help you implement our libraries into your solutions.


The Green Web Foundation has built and maintains several libraries. These libraries allow developers to access peer-reviewed carbon estimation calculations, as well as provide interfaces to surface carbon intensity data.

  • CO2.jsJavaScript

    CO2.js is a JavaScript library that allows developers to estimate the emissions associated with their apps, websites and software.

  • Grid Intensity CLIGo/Golang

    A tool that enables developers and operations teams to surface, monitor, and understand the carbon intensity of the code they run.


The Green Web Foundation has several public API endpoints. These APIs are built on top of The Green Web Foundation's dataset, and provide developers with easy access to a range of data.

  • IP to CO2 Intensity

    Use this API to check the carbon intensity of an IP address based on its real-world location.

  • Greencheck API

    Use this API to check if a domain is hosted on a green web host recognised by The Green Web Foundation.