Today the Black Library has released the Warhammer Age of Sigmar App, complete with every Warscroll.... free automatic updates (please do this for 40k!!), and with what looks like a way to build an army with the My Battle Tool. It also includes the rules.
via the Black Library
Your essential companion to an era of unending war
Access every Warscroll and receive automatic updates when new models are released
Tailor your collection into an army with the My Battle tool
Explore the Age of Sigmar: every book available to download
Includes the rules for playing the Warhammer Age of Sigmar game