Mono
Mono open source ECMA CLI, C# and .NET implementation
...Supported by the .NET Foundation, Mono allows .NET code to run across different operating systems. You can run the mono and mcs test suites with the command; make check. You can verify your installation by using the mono-test-install script, it can diagnose some common problems with Mono's install. Failure to follow these steps may result in a broken installation. The Mono Project (mono/mono) (‘original mono’) has been an important part of the .NET ecosystem since it was launched in 2001. Microsoft became the steward of the Mono Project when it acquired Xamarin in 2016.