Microsoft .NET is MIT: https://github.com/Microsoft/dotnet/blob/master/LICENSE https://github.com/Microsoft/dotnet/blob/master/LICENSE Xamarin/Mono is LGPLv2:

Microsoft .NET is MIT: https://github.com/Microsoft/dotnet/blob/master/LICENSE https://github.com/Microsoft/dotnet/blob/master/LICENSE Xamarin/Mono is LGPLv2: http://xamarin.com/licensing http://xamarin.com/licensing Purchasing a Xamarin license removes the LGPLv2 restrictions. If you have a established open source project then you can apply for free Xamarin licenses @ http://resources.xamarin.com/open-source-contributor.html http://resources.xamarin.com/open-source-contributor.html