One of the biggest rivals for Skype in the VoIP app scene is Viber, with over 200 million users accessing the VoIP service. Today, well over a year since Viber released its first Windows Phone app, the company has now released a version for Windows 8.1 as well.
The app's description on the Windows Store site states that Viber "worked closely with Microsoft to provide the best possible" Windows 8.1 experience. For example, it offers support for notifications of new audio and text chats via Live tiles and the Windows 8.1 lock screen and also can be put into Snap mode for multitasking. The Viber app allows any conversation to be pinned to the Start screen.
Of course, you can make free audio and text calls to any other Viber user and the app can be used to make cheap calls to landline phones as well. Group conversations with up to 40 users are possible and the app allows for any chat to be shared on Viber and Facebook via the Windows 8.1 Share charm.
While there is a way to send video messages via the new Viber app, there is no current way to launch full real-time video chats as with the Skype app. However, folks who don't want or need video calls might want to take a look at this Skype competitor now that it is available for Windows 8.1.