The primary feature is speed. We designed Zappy to work "in flow" and minimize the number of keyboard/mouse interactions. The critical path is: cmd+shift+1 (or whatever shortcut you want) -> drag a box -> press "enter" to immediately get a shareable image (or URL for paid) on your clipboard.

In addition to speed, it's an all-in-one tool that does annotations, GIFs, and screen recording (with optional audio and selfie camera) and we optimized those flow for speed, too.

That is exactly how shareX works.

In comparison, shareX is far more feature rich with the exception of selfie capture.

However, it appears that shareX is only available on Windows and Zappy only on Mac