Reference Guides

Action Tree

by u/nanmaniac

Pathfinder 2E Spell DB (Android and web)

by Tim Scheider aka u/fyjham

Spellfinder 

by u/shinzer0

Archives of Nethys, Pathfinder Reference Guide

 by Blake Davis

Pathfinder 2 System Reference Document

PF2E Tools
(Includes database and encounter builder)

by u/beaushinkle