WhatsApp, available for Android, iOS, WP8, is a wildly popular mobile chat app. You can send text, photos, voice and short video messages to your WhatsApp contacts. It’s easy to install and can synch automaticly your phone’s contacts.
WhatsApp has been acquired by Facebook for $16 billion. On Google Play, the app has over 13.2 million votes giving it just shy of a 5-star rating.