На сайте указано кстати, что он основан на коде Atom.
http://blogs.msdn.com/b/somasegar/archive/2015/04/29/introdu...Visual Studio Code is built on the best of web, native and language-specific technologies. Code builds upon Electron (previously Atom Shell), a cross platform desktop application shell, using Node.js, HTML, TypeScript and CSS. Our engineering team are contributing to the Electron project along with engineers from GitHub, Facebook, Slack and more. Code also uses a newer, faster version of the same industrial-strength HTML-based editor that has powered the “Monaco” code editor used in Azure Websites, OneDrive, Internet Explorer’s F12 tools and more