NumÉcoDiag is a free Chrome extension developed by Mission interministérielle numérique écoresponsable. It aims to facilitate the eco-design self-assessment of digital services. This extension allows users to easily evaluate the eco-design of their digital service or product. It is based on the 79 criteria of the General Digital Service Eco-design Reference Framework (RGESN), which are edited, developed, and made freely available by Mission interministérielle numérique écoresponsable.

The extension presents itself as a form that includes all the criteria of the RGESN. For each criterion, users can choose from four options: To be evaluated, Compliant, Non-compliant, and Not applicable. The data is stored only in the user's browser, with no data collection involved. The extension works offline without any network communication. Users can also export the diagnostic results as a CSV file for further analysis. The source code is available on GitHub and is released under a free license.