ZoomIt is not available for Mac but there are a few alternatives that runs on macOS with similar functionality. The most popular Mac alternative is 
Virtual Magnifying Glass, which is both free and Open Source. If that doesn't suit you, our users have ranked 12 alternatives to ZoomIt and three of them are available for Mac so hopefully you can find a suitable replacement. Other interesting Mac alternatives to ZoomIt are 
DemoPro (Paid) and 
Draw on my screen (Paid).
ZoomIt is a screen zoom and annotation tool for technical presentations that include application demonstrations. If you're looking for more info about ZoomIt like screenshots, reviews and comments you should visit our info page about it. Below you find the best alternatives.
Virtual Magnifying Glass, a free, open source, screen magnification program for Windows, Linux, FreeBSD and Mac OS X. Free full version download and instructions for use. Latest Features: New, much improved dynamic mode for Windows 2000+! No longer requires DirectX or a special video card. New, improved Mac OS X version, much smaller, no longer requires Qt. Show the center pixel's RGB values, in both decimal and hexadecimal.
DemoPro is a menu bar app to aid with live demonstrations and presentations of applications or websites. DemoPro has no interface in order not to distract your audience. Each tool has its own hotkey which can be customized by going to DemoPro in the menubar. DemoPro makes it super easy to draw on any app or web page while you do a demo or record a tutorial. No matter what's on your screen, just press a hotkey to activate the drawing tool of your choice (arrow, rectangle, or freehand).
Examples: - Add handwriting/drawings during slide presentation for better illustration - Add temporary notes on screen to mark documents of other apps - Outline objects on screen and keep the drawings for reference to use in another screen view - Simply doodle as you go
