Inside the world of WhatsApp

Jan is barefoot; Brian wears flip-flops. Both are walking around in bermudas and a t-shirt. "You're the first journalist to come in here," they say by way of welcome. This is the general headquarters of WhatsApp, one of the world's most popular applications for smartphones. Jan Koum, 36, a Ukranian, and Brian Acton, 40, an American, will reveal nothing about themselves except what's on their website, namely that "WhatsApp was founded by two guys who spent a combined 20 years doing geeky stuff at Yahoo! Inc. before starting WhatsApp Inc."

In fact, they guard their privacy so jealously that it is almost unnatural. "We're not a huge corporation with thousands of workers," exclaims Koum. Asked about their lives, they say they would rather "keep a low media profile, as a business and as individuals."

If you carry a smartphone around in your pocket, there us a good chance that you no longer send SMS text messages, but use WhatsApp instead. This mobile messaging application saw the light in August 2009, and since then has been downloaded 50 million times from Google's Play store. It is available for iPhone, Blackberry, Windows Phone, Android and Symbian (Nokia's operating system) and it is not limited to text messages; users can send videos, photos and voice messages as well, at no cost except for an annual fee of one dollar (0.79 euros).

WhatsApp is located in Mountain View - that is as much as the website will say; incidentally these days the site also includes the following message in small type: "Congratulations to Spain for winning Euro 2012!!!". But the leads end there. There is no sign at the building entrance, and no sign on the door of its office, either. Inside there is a spacious open room of around 100 square meters, with graffiti on the walls and a jumble of tables, cables and computers in the middle. The bosses have no office of their own, instead they sit with the rest of the workers - 30 full-time employees and five part-timers. Most of what they do here is customer service, since technical development is carried out in Russia, "where there are excellent engineers," says Koum.

The experience is always better if you don't have bothersome banners distracting you"

Their stated goal is to "develop a good product." "To create something that is used by millions of people is the best thing a engineer can experience," they say. And for that, there is no need to be in the spotlight. When they were awarded the best application prize at the last Mobile World Congress in Barcelona, Koum flew there but sent his marketing representative to pick up the award, which is now stored away in the garage. "I was at a meeting," he says with a smile.

These former Yahoo! employees feel "normal," and "that's the way they want to remain," confirms the business chief, Neeraj Arora. Eventually, after learning that the photographs for this article would be taken with a telephone and not an actual camera, they agreed to sit at their desks, trusting in the technical limitations of the reporter's device.

At least a billion messages were circulating every day through WhatsApp in February of this year. The application remains among the most popular downloads in 40 countries in the European Union, Asia, the Middle East and Latin America. In Germany it was the top download of 2011 and there were over six million downloads in Spain, according to Xyologic, an application search company.

But these figures do not keep them up at night. "We don't pay attention to the volume of downloads, sent messages or the number of minutes that people chat," they say, although that is hard to believe, especially when Koum adds with a sly smile: "We are growing fast, because the world is moving to the smartphone and we have taken advantage of this revolution."

We don't register age, gender or address. We don't need it"

Except for Apple, all other platforms offer free WhatsApp for the first year, then charge a dollar for an annual subscription. "It's a fantastic offer for what we offer [chat, video, audio, photo in the profile, blocking for privacy purposes...]," says Acton.

Sending a message costs nothing and nobody has to worry about the other person's mobile model because the application is cross-platform. Its founders insist their success is due to their quality, not because of the money people save. "Price is secondary. People simply want to be in touch. Smartphones are increasingly affordable and accessible, even in emerging countries, and they have a data plan associated to them. As penetration advances, there is a migration to our systems, because we provide a good service. In the end it's a matter of marketing," says Acton.

Their success is due to word of mouth, they say, because WhatsApp does not advertise itself. "You trust a friend more than any other source, right?" asks Acton.

"Everything is tied to our rejection of advertising," adds Koum. "The experience is always better if you don't have bothersome banners distracting you."

Both deny that WhatsApp makes money by selling its clients' address book.

"That is absolutely false," says Acton vehemently. "We oppose data tracking. It is in our DNA as a company and as people. We value privacy and security tremendously. To do that would be to go against our principles."

"We don't even register age, gender or address. We don't need it," says Koum. "All we know is the user name, which does not have to be a real name, and the telephone number. The number is the only essential element for chatting. We worked for a long time at Yahoo! and when we left we decided to create something that would have nothing to do with this model where the user is the product - something that would be a more conscious, private experience."

Apple eliminated WhatsApp from its application store for a while, but its founders say it was only for four days, and not because of security reasons. Asked if they are planning an IPO, Acton said that "for now, the main thing is to grow."