See:
https://github.com/Microsoft
https://www.microsoft.com/net
http://www.typescriptlang.org/
https://github.com/Reactive-Extensions/RxJS
https://github.com/Microsoft/BashOnWindows
https://github.com/Microsoft/ChakraCore
and so on... not to mention their own contributions elsewhere including Electron itself. I know some of their Azure Cloud solutions are open source as well.
See:
https://github.com/Microsoft
https://www.microsoft.com/net
http://www.typescriptlang.org/
https://github.com/Reactive-Extensions/RxJS
https://github.com/Microsoft/BashOnWindows
https://github.com/Microsoft/ChakraCore
and so on... not to mention their own contributions elsewhere including Electron itself. I know some of their Azure Cloud solutions are open source as well.