在构建2014年，微软宣布其下一代编译器codenamedRosyln将作出开源，并提供的 Github上。

At Build 2014, Microsoft announce that their next generation of compilers codenamed "Rosyln" would be made open source and be available on Github.

在传统的C＃编译器从微软不是开源的，虽然它是免费的，通过的Visual Studio防爆preSS 或.NET Framework SDK。但也有免费的，开源的，C＃编译器在那里。请查看单

The legacy C# compiler from Microsoft is not open source, although it is freely available through Visual Studio Express or the .NET Framework SDK. However there are freely available, open source, C# compilers out there. Check out Mono