The mobile messaging application Whatsapp is finally free on Apple's iOS. The successful mobile chat tool used to cost $0.99 on iOS and was the sixth most popular paid app by Apple.

After a free download, iOS users have access to all the features of the app for 12 months. But a year down the lane they will have to pay $0.99 for an additional year. The move doesn't affect existing iPhone users. Moreover, the subscription model will be of service for just some time.

Whatsapp is available free for iPhone users from today
Whatsapp is available free for iPhone users from today

The cross-platform mobile messaging app was always free for Android and Windows smartphones, but iOS did contribute to make it among the top revenue grossing apps.

The move can be seen as an attempt to gather a bigger user base. The popular messaging app already caters to over 250 million monthly active users, a bigger crowd than what Twitter pulls in. On its best days, more than 27 billion messages were sent using the mobile app.

The popularity of this app is not just that it works on any mobile operating system - Android, iOS, Windows, but also that the company is strictly against advertising.

When Whatsapp announced its 250 million users mark, WhatsApp CEO Jan Koum said, "We do have a manifesto opposing advertising. We're proud of that. Who likes advertising?"

The app now offers a few pleasant add-ons for iPhone users. For instance, new Whastapp users can send multiple photos to someone at the same time. Furthermore, there is now an option to backup and restore iCloud chat history.

WhatsApp was founded in 2009 and took a considerable time to become a sensation. It worked on a single $8 million funding from blue-chip venture capital firm Sequoia Capital and other investors in 2011. It will soon be a necessity app, just as how BlackBerry messenger was for office workers.

To download the Whatsapp free on the iTunes App Store, click here.