Jagex launched its new companion app for RuneScape just prior to the holidays. The new app in its current form allows players to chat with friends and clan members from their mobile devices. While the current version only offers chat options, additional features are planned for deployment throughout 2014. The app is currently available for iOS, Android and certain PC browsers. You can find out more about the app and requirements on the RuneScape website.

Source: RuneScape Companion App Announcement, Companion App FAQ