On which mobile platform was WhatsApp first released?

WhatsApp was first released on the iPhone (iOS). The app appeared on Apple’s App Store in May 2009, before versions for BlackBerry, Symbian, Android, or Windows Phone were available.

WhatsApp began as a simple status-updating application created by Jan Koum and Brian Acton, former Yahoo employees. Koum had recently bought an iPhone and saw the App Store as a promising new platform for mobile software. Apple’s introduction of push notifications soon helped WhatsApp evolve from a status tool into an instant-messaging service.

A common mix-up is confusing WhatsApp’s first platform with its first major messaging audience. BlackBerry support followed shortly afterward, in June 2009, and was important because BlackBerry Messenger was then extremely popular. Android support came later, in 2010. The iPhone launch therefore refers to WhatsApp’s earliest platform release, not necessarily the platform where it first became widely popular.