Cross-platform messenger WhatsApp; Image by None via CrunchBase  WhatsApp, the mobile messaging service that sends free texts, photos, videos and audio messages, now has more than 400 million people using the service on a monthly basis, the startup revealed Thursday. That’s a rapid escalation from the 350 million active users it announced in October and easily makes it the largest, cross-platform mobile messaging service in the world.  The Mountain View, Calif-based app has more monthly active users than Twitter’s 232 million, and while it’s still well behind Facebook’s 1.2 billion active users, WhatsApp is at the forefront of a global phenomenon in which mobile services appear to be pulling users away from traditional social networks. Its growth curve could be as concerning for Facebook as it is for wireless carriers, whose SMS SMS revenues have fallen prey to the competition from free messaging services in the last few years.  “We are excited to have reached 400 million monthly active users, and even more excited to have achieved this without spending a dollar on marketing,” said co-founder and CEO Jan Koum in an e-mailed statement. “Our growth has been driven by our users, and we want to thank each and every one of them for their support over the years.”  The company also gave updated stats on its daily message flow: WhatsApp’s users are now sending 16 billion messages per day on average, receiving 32 billion, and sending 500 million images per day. That’s well above the 400 million photos received daily by people who use Snapchat, a company that Facebook reportedly tried to buy for $3 billion.  WhatsApp has become something of a nonconformist in the hot, mobile-messaging space. It refuses to show ads, citing in its rationale the “Fight Club” rant by Tyler Durden against an industry that “has us chasing cars and clothes, working jobs we hate so we can buy shit we don’t need.” Unlike other large messaging services like WeChat, LINE and Kik, WhatsApp also hasn’t gone down the route of building out a platform on which users can play games, stream YouTube videos or buy digital stickers. Instead it charges a $1 annual subscription after one free year, for a service which customers will largely use to send text messages, links and photos. This simple business model has so far kept it profitable.  The startup’s primary venture capital investor is Sequoia Capital, which put $8 million into the company in a funding round in early 2011; WhatsApp appears to have raised no further cash from VCs since then.  “They charge a modest fee for a service that replaces SMS,” said WhatsApp’s lead investor at Sequoia, Jim Goetz. “It’s private, and the vast majority of user are happy to pay.”  WhatsApp’s closest competitor, the Japanese messaging platform LINE, claims to have 300 million registered users, though the rival won’t break out how many of them are active. Not far behind is China’s WeChat with 270 million registered users and KakaoTalk of South Korea with 110 million. Kik is another messaging services from Canada which claims 100 million registered users and is popular among teens and students in the U.S.  WhatsApp co-founder Jan Koum; Image by None via CrunchBase  Recent analysis suggests Kik may be hot on the heels of WhatsApp in the United States, and the app’s founder, former BlackBerry engineer Ted Livingston, believes strongly that messaging services need to build platforms to survive in the coming years. His own service is evolving into a HTML5 mobile browser, with messaging as its core feature.  “It’s really interesting because right now there are five big messengers,” Livingston said. “Four of them are building a platform, and only WhatsApp is not.” The company, he added, “probably feels they have won.”  Those are fighting words, but WhatsApp has managed to get this far because of what it calls “the organic growth” of its user base and barely any marketing spend. That means it may have enough momentum to benefit from the same, sprawling network effect that over time pushed Facebook into the stratosphere of more than one billion users; its use case having shifted from fun, social network, to obligatory communication utility. WhatsApp’s use case seems to have similarly evolved from being a novel, inexpensive way to stay in touch, to a go-to communication tool.  WhatsApp said it had become a necessary messaging tool in a number of countries, particularly in the developing world. In India, it said, Mumbai doctors use it to send real-time photographs of their patients ECG results to a group within the app of cardiac doctors, cutting through red tape and saving lives.  Despite its growth, WhatsApp has plenty of competition riding its coat tails, with startups moving in with novel features like self-destructing texts (the apps Frankly and Wickr) or anonymous secret sharing (Whisper). Having launched in 2009, WhatsApp was among the first mobile messaging apps to become available on iPhones, before moving on to Nokia Nokia, BlackBerry and Android phones, and was also among the first to sync with users’ address books.  That first-mover advantage and ease of connecting with an established network without having to create a username, have all helped WhatsApp steadily grow to its current, international size. Its presence in the U.S. is still relatively small, but it’s said to be on more than 95% of all smartphones in Spain and massive in countries like Brazil. “I was in Hong Kong last week and every single person was on WhatsApp,” Kik’s Livingston admits. He still contends that the company’s lack of games, in-app service and stickers could see it lose out to LINE, WeChat or his own services.  WhatsApp’s founder Koum, however, appears to have a single-minded focus on being communication tool that simply works for users. So long as his service remains necessary for enough people to communicate, that growth could well continue.
The maverick messaging app has become the biggest in the world despite almost zero marketing, limited venture capital and none of the fancy features of its rivals.