Have an Xbox One? You will want Xbox One SmartGlass.

This free app shows your Xbox One friends, activity feed, achievements, game clips, and more, right on your tablet or phone.

Windows 8 Compatible devices:
Windows 8 and Windows RT Tablets and PCs
Windows Phone
Windows Phone compatible devices:
Windows Phone 8.0 or higher
Apple iOS
iOS compatible devices:
iPod Touch (4th and 5th generation); iPhone (3GS, 4, 4S, 5, 5C, 5S); iPad (2, 3, 4 and Air); iPad Mini (1st and 2nd generation)
Android compatible devices:
Supports Smartphones and tablets 7" and larger that run Android 4.x or higher