Jan Koum, founder of WhatsApp — the popular mobile messaging and voice calling application, has once again given tribute to FreeBSD and spoke of his beginnings at Yahoo. You can read the full article at Wired. WhatsApp is used by 900,000,000 users around the world.

FILE -- WhatsApp founders Brian Acton, left, and Jan Koum at company headquarters in Mountain View, Calif., May 23, 2013. The frenzy to acquire fast-growing technology startups reached new heights on Feb. 19, 2014 as Facebook announced its largest ever acquisition, saying it would pay at least $16 billion for WhatsApp, a text messaging application with 450 million users around the world. (Peter DaSilva/The New York Times)

FILE — WhatsApp founders Brian Acton, left, and Jan Koum at company headquarters in Mountain View, Calif., May 23, 2013. The frenzy to acquire fast-growing technology startups reached new heights on Feb. 19, 2014 as Facebook announced its largest ever acquisition, saying it would pay at least $16 billion for WhatsApp, a text messaging application with 450 million users around the world. (Peter DaSilva/The New York Times)

http://www.wired.com/2015/10/whatsapps-co-founder-on-how-the-iconoclastic-app-got-huge/