When Facebook acquired WhatsApp four years ago, the number of messages being sent via the messaging platform was about a third of what it is today. As of May 2018, about 1.5 billion users are sending 65 billion messages via the WhatsApp mobile app and web client per day. That's up from one billion a couple of years after the company launched in 2009. Given that Facebook has a messaging app of its own analysts weren't sure what an app like WhatsApp could bring to the table.