Rosenstein grew up in San Francisco Bay Area and attended The College Preparatory School in Oakland, CA. He was a successful high school Lincoln–Douglas debater. He pursued an undergraduate degree in mathematics at Stanford University.
Rosenstein dropped out of a graduate program in computer science at Stanford University in 2004 to join Google as a software engineer. At Google, Rosenstein also worked as product manager for Google Page Creator. Page Creator was later restricted in sign ups to just 3 million users as new users were asked to use Google Sites instead. Finally, to focus on another Google Webpage-publishing service called Google Sites, all existing content on Page Creator was transferred to Google Sites in 2009. He was working on project code named Platypus in 2006.
In 2007, he left Google for a lead engineer position at Facebook working closely with Mark Zuckerberg and Dustin Moskovitz. He was an Engineering Technical Lead at Facebook.com from May 2007 to November 2008. He was compensated with 4,863,335 Class B shares of FB ($130 million at $27/share), which he has deposited into a trust.
At Facebook, he was technical lead in charge of Facebook's Pages, Facebook's "Like" button, and was responsible for Facebook Beacon, the site's controversial advertising program that was terminated in a 2009 class-action lawsuit.
Asana has 35 employees as of Oct 2012 with company valuation at USD 280M at its latest round of funding by then.
- "Facebook co-founder Dustin Moskovitz leaves for start-up" Los Angeles Times, 3 October 2008
- "Insider Perspectives: Ex-Googler Justin Rosenstein on Making the Jump to Facebook" Inside Facebook, 9 July 2007
- "Justin Rosenstein" CrunchBase no date.