WhatsApp is an instant messaging app for smartphones that operates under a subscription business model. The proprietary, cross-platform app uses the Internet to send text messages, images, video, user location and audio media messages.
In January 2015, WhatsApp was the most globally popular messaging app with more than 700 million active users, with India alone having a user base of more than 70 million.
WhatsApp Inc., based in Mountain View, California, was acquired by Facebook on February 19, 2014, for approx. US$22 billion.
Viber is an instant messaging and Voice over IP (VoIP) app for smartphones developed by Viber Media. In addition to instant messaging, users can exchange images, video and audio media messages. The client software is available for Mac OS, Android, BlackBerry OS, iOS, Series 40, Symbian, Bada, Windows Phone, and Microsoft Windows. A 64-bit Linux version is available in both .deb (Debian & Ubuntu) and .rpm (Fedora & openSUSE) package formats. Viber first requires installation on a phone in order to work on a desktop operating system environment. Viber has over 100 million monthly active users from its 280 million global registered users.