Jan Koum (born Jan Borysovych Koum on February 24, 1976, in Kyiv, Ukraine) is a Ukrainian-American billionaire entrepreneur, computer programmer, and philanthropist best known as the co-founder and former CEO of WhatsApp, a revolutionary mobile messaging application. Born into a Jewish family during the Soviet era, he immigrated to the United States in 1992 at age 16, settling in Mountain View, California, where his family faced economic hardship. Self-taught in programming, he worked at Ernst & Young and Yahoo before co-founding WhatsApp with Brian Acton in 2009. The app's explosive growth led to its acquisition by Facebook (now Meta) in 2014 for $19.3 billion, making Koum a billionaire. He served as CEO until 2018, stepping down amid reported tensions over privacy policies. Post-WhatsApp, Koum has focused on tech investments through his venture firm and philanthropy, particularly supporting Jewish and pro-Israel causes, including major donations to AIPAC and initiatives aiding Ukrainian refugees and immigrant rights. As of October 2023, Forbes estimates his net worth at $15.2 billion. Koum maintains a low public profile, valuing privacy in line with WhatsApp's ethos, and resides in California. His journey from poverty to tech titan underscores themes of immigration, innovation, and the American Dream, though WhatsApp has faced criticism for its role in spreading misinformation despite its encryption features.