Screen annotation software to draw on any app in OSX I want to draw on any app pdfs, videos, code. It would be helpful to aid in demonstration in a class setting for me. Do you know if any such app exists that does not require an external pen i.e. using mouse or trackpad to draw.
Check out Snappy App - it allows you to grab any part of your screen and float it above the screen - then you can draw on it, change its transparency, shrink it down, whatever. There's a free version which does more or less all you'd want and the in-app purchases are very cheap (you need an in-app to draw on things).
I've also just recently been introduced to https://presentify.compzets.com/ which takes a different approach but might also meet the requirements.