High Quality Content by WIKIPEDIA articles! WhatsApp Messenger is a proprietary, cross-platform instant messaging application for smartphones. In addition to text messaging, users can send each other images, video, and audio media messages. The client software is available for Android,BlackBerry OS,iOS,Series 40,Symbian, and Windows Phone. The company by the same name was founded in 2009 by Brian Acton and Jan Koum, both veterans of Yahoo and is based in Santa Clara, California.