In 1993, as a graduate student, he co-wrote NCSA Mosaic for Windows with fellow student Chris Wilson while working at the National Center for Supercomputing Applications (NCSA).[1] Mittelhauser was part of the original team of five programmers of Mosaic with Marc Andreessen and Eric Bina (Unix version), Aleks Totic (Mac version) and Chris Wilson (Windows version).[2][3][4] The Windows version that Mittelhauser and Wilson wrote was the first browser with over a million downloads and is often characterized as the first widely used web browser.[5] Mittelhauser is considered a founding father of the browser.[6][7]
Mittelhauser led the software organization at OnLive, Inc. and managed their successful launch in 2010.[9] He left at the end of that year as VP of Engineering and joined their Technical Advisory Board.
In May 2012 he became Vice President of Engineering for Nebula, Inc.[9]
From December 2014 to December 2016, he was chief executive officer of the software company that develops CloudBolt.[10][11]
Mittelhauser has two daughters and lives in Silicon Valley. In 1999 he opened The Basin restaurant in Saratoga with fellow Netscape-er Bill Foss.[13][14]