Free. Cross-platform. Open source. A platform to build Android and iOS apps using.NET or C#. You can create native apps for billions of Android, iPhones, iPads, Macs, and Windows devices using.NET or C#. You can also share code with any.NET application, enabling you to be more productive and create apps faster across all platforms. Are you ready to take code sharing to the next step? Xamarin.Forms, an open-source mobile UI framework by Microsoft, allows you to build iOS, Android, and Windows apps with.NET using a single codebase. Xamarin.Forms can be used to create a consistent look across all platforms. .NET is a platform for developers that includes tools, programming languages and libraries to build many types of applications. Xamarin is an extension to the.NET platform that provides tools and libraries for building apps for Android and iOS, tvOS and watchOS, macOS and Windows.