The CommunityToolkit.Mvvm package (aka MVVM Toolkit, formerly named Microsoft.Toolkit.Mvvm) is a modern, fast, and modular MVVM library. It is part of the .NET Community Toolkit and is built to be platform and runtime independent, simple to pick-up and use, à la carte, and providing a lean and performant reference implementation for all basic MVVM building blocks. The MVVM Toolkit is maintained and published by Microsoft, and part of the .NET Foundation. It is also used by several first party applications that are built into Windows, such as the Microsoft Store. The toolkit is available on GitHub at http://aka.ms/windowstoolkit.
This is a sample app which demonstrates a wide variety of features available to developers. It contains examples and documentation for various components.