With over 1 billion users, it is already the world's most popular messaging service, but WhatsApp is now seeking to extend its reach by offering its users access to most of its features on Windows and Mac computers.

In a move that will be seen as a challenge to other messaging apps like Apple's iMessage, Facebook's Messenger and Google Hangouts, the launch of dedicated apps for Windows 8, Windows 10 and Mac OS X could have the biggest impact on Skype, the video and audio service with 300 million users.

With the addition of desktop apps, WhatsApp is now available pretty much everywhere: On all major smartphone operating systems (Android, iOS and Windows Phone), through web browsers and now on the most popular desktop operating systems. The desktop software will allow users to message friends sending images, video and audio files, but initially at least, it won't allow for voice calls to be made.

The only other app with such ubiquity is Skype and with video-calling still not available on WhatsApp, it retains a key appeal for users. However, code within a beta version of its iOS app indicated that video calling is being developed and if this is rolled out to all platforms, it could have a significant impact on Skype's business.

The benefits of using a dedicated desktop app include the ability to utilize native notifications (which are vital for instant messaging services) as well as easier keyboard shortcuts. To use WhatsApp on the desktop, users need to scan a QR code from within WhatsApp on their smartphones and messages will be synced.

WhatsApp earlier this year scrapped its $0.99 annual subscription fee, meaning it is in search of a revenue stream, which it says won't come from third-party ads but by opening up the service to allow businesses to connect directly with consumers. WhatsApp was acquired by Facebook for $19 billion in 2014 but remains a relatively independent entity within the social network where one of its mains rivals is Facebook Messenger.

WhatsApp, which recently rolled out end-to-end encryption for all users by default, ran into trouble in Brazil last week when a judge ordered the app be banned in the country for 72 hours.