Jon DeVaan was a former senior vice president for Windows Development at Microsoft. DeVaan began at Microsoft as a programmer on a database product called Microsoft File for the Macintosh. He would become part of the Microsoft Excel founding team. Eventually, he would help create Microsoft Office, staying on until Office 2000. Later he would lead the Windows Core Operating System Division (COSD), the division responsible for the core components and architecture of Microsoft Windows. As head of the COSD, he would participate in Window 7, Windows Vista, and Windows 8 development.