F + S TYPE

The Typography Manual has several useful features and resources for designers, including a visual type anatomy glossary, a font size ruler, an em calculator, and enough content to fill a 60-page book. It has all the essentials of a desk reference in a regularly updated pocket resource.
I think this is a pretty good idea for beginner designers, but I don't see an experienced designer ever having to use this app.

TYPE APP FOR IPHONE