Mobile messaging is huge in tech right now and consolidation is coming fast, as evidenced by the recent acquisition of Viber for $900 million and WhatsApp for a jaw-dropping $19 billion in cash and stock. At the heart of it all is the attractiveness of their user base; in the case of WhatsApp, the service is on the path to connect 1 billion people, and with higher engagement than Facebook itself it was a key move to dominate the mobile space.

Messaging is not only among the top activities on smartphones (if not THE top activity), messaging apps are increasingly seen as social networks. After all people use them to send each other texts, videos, photos and other content either one-on-one or as a group. Sounds familiar, right?

While WhatsApp is an international phenomenon, it still isn't as big a deal in the US. It's also purposely light on features due to a ?no ads, no games, no gimmicks? policy. But as it is with any hot trend, there's no shortage of alternatives. Below is our side-by-side feature comparison for today's top contenders this side of the globe, followed by some notes on each company's Terms of Service and Privacy Policy to give you some perspective on where they stand.