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CONTRIBUTING.md

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+# Contributing to CO2.js
+
+Thank you for considering contributing to CO2.js. Open source is at the heart of our work, and we welcome input and contributions from the community across all our projects.
+
+## Getting Started
+
+- Submit a [new issue](https://github.com/thegreenwebfoundation/co2.js/issues/new/choose), or add additional comments to an [existing issue](https://github.com/thegreenwebfoundation/co2.js/issues).
+  - Our issue template provide you with a scaffold to follow when raising a new issue.
+    - For bugs, clearly describe the problem you are facing including steps to reproduce when it.
+    - For new features, clearly describe the new feature you'd like to see added and provide a reason for why it should be added.
+    - To request a carbon estimation model be added to CO2.js, please provide as much information about the model as possible including links to additional documentation and information about how the model is licensed.
+- For bug reports, please also be sure to include the information about the environment your code was running in (e.g. NodeJS, Deno, Edge Worker, Browser etc).
+
+Changes made that are not linked to an existing issue will not be accepted.
+
+## Making Changes
+
+- Fork the repository on GitHub.
+- Create a topic branch from where you want to base your work. This branch should usually be based off `main`.
+- Make commits of logical units.
+- Make commit messages clear and understandable.
+
+## Submitting Changes
+
+- Push the changes made in your branch to your fork of this repository.
+- Submit a pull request this the repository in the `thegreenwebfoundation` organization.
+  - Your pull request description should follow the structure outlined in our pull request template.
+  - Be sure to clearly explain the changes you have made, any new files, dependencies, or network requests that have been added, and provide any additional context to help reviewers understand the changes made
+- You pull request will be reviewed by a maintainer from Green Web Foundation.
+- After feedback has been given we expect responses within two weeks. After two weeks we may close the pull request if it isn't showing any activity.
+
+## Code of Conduct
+
+Please note that this project is released with a [Contributor Code of Conduct](https://github.com/thegreenwebfoundation/.github/blob/main/CODE_OF_CONDUCT.md). By participating in this project you agree to abide by its terms.
+
+## Thank you
+
+Again, thank you for your contributions. We appreciate your help improving CO2.js, and we look forward to your future contributions.