Michael Seibel

Michael Seibel is a seasoned entrepreneur, investor, and startup advisor, renowned for co-founding the live-streaming platform Justin.tv (which evolved into Twitch) and the mobile video app Socialcam. Socialcam was acquired by Autodesk in 2012 for $60 million. From 2016 to 2024, Seibel served as the CEO of Y Combinator, a leading startup accelerator. In March 2025, after over 12 years at Y Combinator, he transitioned to a "Partner Emeritus" role, allowing him to continue mentoring founders while exploring new ventures.

Born in Brooklyn, New York, Seibel spent his early years in East Brunswick, New Jersey, and graduated from East Brunswick High School in 2000. He earned a bachelor's degree in political science from Yale University in 2005. Before embarking on his entrepreneurial journey, Seibel worked as a finance director for a U.S. Senate campaign.

In 2006, Seibel joined Justin Kan, Emmett Shear, and Kyle Vogt to launch Justin.tv, which debuted in March 2007 as an online reality show featuring Kan broadcasting his life 24/7. The platform later expanded to allow anyone to broadcast live video. By 2010, Justin.tv had become profitable, and the team began developing new projects within the company, including Socialcam and Twitch.tv.

Socialcam offered a simple way to capture and share videos from smartphones. It officially spun out as a separate company in early 2012, with Seibel and co-founders Guillaume Luccisano and Ammon Bartram at the helm. The company joined the Y Combinator winter 2012 class and rapidly grew, accumulating over 13 million iOS and Android downloads within months. Following the sale of Socialcam to Autodesk, Seibel returned to Y Combinator as a part-time partner, where he continued to mentor and support startups.

In addition to his work at Y Combinator, Seibel serves on the boards of Reddit and Dropbox. He has also made personal investments in several successful startups, including Cruise, Brex, Figma, Rippling, and Clipboard Health.