Microsoft seems to have committed to open-source software over the past few years, letting the community contribute to things such as PowerShell and the old File Manager from Windows 3.0. But there's more to be opened up to the world, and now Microsoft has announced that the Windows Calculator app is now open-sourced and available on GitHub.
This isn't any old version of the Calculator app, either. It's the app that ships with Windows 10, so contributions here can likely improve the experience for everyone. Of course, any contributions you make will have to go through Microsoft, and you can head here to learn more about the requirements for changes to be approved for a production release.
Otherwise, the process will work similarly to any other project on GitHub. Developers can participate in discussions, suggest ideas, report issues, or do the hard work themselves, if they so prefer.
Microsoft also emphasizes that exploring the code for the Calculator app may be a good learning experience, teaching developers about the Universal Windows Platform, XAML, Fluent Design, and Azure Pipelines. You can also reuse the code to build your own projects, and Microsoft will be bringing custom controls and API extensions from the app into the Windows Community Toolkit and the Windows UI Library. To check out the code for the Calculator app, head to the respective GitHub page to get started.