Founder Profile
Jack Dorsey
Last reviewed: October 2026 · By Swet Parvadiya
Who is Jack Dorsey?
Jack Dorsey is a founder of Block Inc, which was founded in 2009 with Jim McKelvey. Jack Dorsey is a founder of X Corp (formerly Twitter), which was founded in 2006 with Evan Williams, Biz Stone and Noah Glass.
- Companies founded
- Block Inc and X Corp (formerly Twitter)
- Founded
- 2009
- Co-founders
- Jim McKelvey
Background
Jack Dorsey was born on November 19, 1976, in St. Louis, Missouri. As a teenager he wrote dispatch-routing software and worked for Jim McKelvey's St. Louis business. He studied at Missouri University of Science and Technology and New York University without graduating. He co-founded Twitter in 2006 and was its first chief executive until 2008, returned as executive chairman in 2011, served as chief executive again from 2015 until November 2021, and left its board in 2022. He is an outspoken bitcoin advocate.
Founding Story
Dorsey co-founded Square in 2009 with Jim McKelvey after McKelvey lost a glass sale he could not take by card, and has run the company ever since: through the 2015 IPO, the rise of Cash App, the December 2021 rename to Block, the Afterpay purchase and, in February 2026, a cut from more than 10,000 employees to just under 6,000 that he tied to AI. His title is Block Head and Chairman. Between 2015 and 2021 he was also Twitter's chief executive, an arrangement investors repeatedly questioned until he left Twitter to focus on Block.