WhatsApp: The inside story (Wired UK)

For more co-founder details, see Facebook turned down WhatsApp co-founder Brian Acton for a job in 2009 (TNW)

"An émigré at 16 from Communist Ukraine -- where phones were routinely tapped, and classmates questioned for mocking politicians -- Koum and his mother could rarely afford to call family back home.

So when, at 31, he left a job at Yahoo! with enough cash to launch his own business, it made absolute sense that he would work on democratising phone-based communications. He had just three rules as he experimented with the early iterations: his service would defiantly not carry advertising, an experience satisfyingly absent from his Soviet upbringing; it would not store messages and thus imperil individual citizens' privacy; and it would maintain a relentless focus on delivering a gimmickless, reliable, friction-free user experience."

WhatsApp: The inside story (Wired UK)