"Here are four numbers that tell the story of WhatsApp: 450, 32, 1 and 0.
450. WhatsApp has more than 450 million active users, and reached that number faster than any other company in history. [...]
32. Even by the standards of the world’s best technology companies, WhatsApp runs lean. With only 32 engineers, one WhatsApp developer supports 14 million active users, a ratio unheard of in the industry. [...]
1. Jan keeps a note from Brian taped to his desk that reads “No Ads! No Games! No Gimmicks!” It serves as a daily reminder of their commitment to stay focused on building a pure messaging experience. [...]
0. There may be no greater testament to the viral nature of WhatsApp than the fact that the company has accomplished all this without investing a penny in marketing. [...]"