Before founding WhatsApp, Jan Koum and Brian Acton worked at which web company? Jan Koum and Brian Acton both worked at Yahoo.
Koum joined Yahoo in 1997 as an infrastructure engineer after meeting Acton while working at Ernst & Young. Acton had joined Yahoo the previous year, and the two spent roughly nine years working together there. Their experience involved large-scale internet infrastructure and helped form the professional partnership that later produced WhatsApp.
They left Yahoo in September 2007 and took about a year away from regular work, traveling around South America and playing ultimate Frisbee. Both later applied for jobs at Facebook but were rejected. Koum began exploring a mobile application after buying an iPhone in January 2009, and Acton eventually joined the project.
Acton helped secure $250,000 in seed funding from former Yahoo colleagues in October 2009, strengthening his claim to co-founder status. Facebook acquired WhatsApp in 2014 for approximately $19 billion in cash and stock, making their Yahoo connection an important part of the company’s origin story.