High Quality Content by WIKIPEDIA articles! Windows Runtime, or WinRT, is a platform-homogeneous application architecture on the Windows 8 operating system. WinRT supports development in C++/CX (Component Extensions, a language based on C++) and the managed languages C# and VB.NET, as well as JavaScript and TypeScript. WinRT applications natively support both the x86 and ARM architectures, and also run inside a sandboxed environment to allow for greater security and stability.