I've been using Grimoire from the windows store however the more I use it the more things wrong I'm finding with it. What is your favorite app for looking through spells?
On the Google playstore, there is an app called Pathfinder Spellbook from TnT Game Studios. It is a good spellbook app. You can have a separate spellbook for each character. It does Oracle Mystery spells. You can pick spells by school.