WhatsApp's story is the kind that feeds the dreams of programmers and entrepreneurs the world over.

Tired of collecting customer data for marketing pitches, Yahoo's Jan Koum, 38, and Brian Acton, 42, quit the company to develop an easy-to-use messaging app. Their unique approach paid off when WhatsApp, which has amassed 450 million users since its launch in 2009, announced last week they'd sold it for $19 billion to Facebook, making it the biggest Internet deal since the $124 billion merger of Time Warner and AOL in 2001.

Founders

For Koum, the story is one of a modern-day American dream. He was born in Ukraine during a time when it was not uncommon for a person's phone lines to be tapped - an experience that instilled in him the importance of privacy, shared by Sequoia Capital Ltd. Partner Jim Goetz, the app's investor. His family immigrated when he was just 16 years old, relying on food stamps to scrape by.

Acton, meanwhile, hails from Michigan. With a background in advertising, travel and shopping services, he climbed to the #44 employee spot at Yahoo in 1996. He lost millions of his money in the dot-com boom and subsequent bust, and disclosed on Twitter that he was turned down for a job at Facebook in 2009.

Different approach

The WhatsApp application is unique in that it doesn't gather data such as names, addresses, age or gender, instead simply approving users if their numbers successfully pass a quick authentication process.

"Jan's childhood made him appreciate communication that was not bugged or taped," Goetz wrote in a company blog post. "When he arrived in the U.S. as a 16-year-old immigrant living on food stamps, he had the extra incentive of wanting to stay in touch with his family in Russia and the Ukraine. All of this was top of mind for Jan when, after years of working together with his mentor Brian at Yahoo, he began to build WhatsApp."

Going forward

Going forward, Koum will join Facebook's board of directors and WhatsApp will continue to function with relative independence from the social media giant in a way reminiscent of Instagram.

"Facebook has assured Jan and Brian that WhatsApp will remain ad free and they will not have to compromise on their principles," Goetz wrote. "We know that Jan, as a new member of Facebook's board, will continue to champion the rights of WhatsApp users."