Flameshot - Powerful yet simple to use screenshot software for Linux.
Greenshot - Greenshot is a free and open source screenshot tool that allows annotation and highlighting using the built-in image editor.
Spectacle App - Move and resize windows with ease.
maim - maim (Make IMage) is a spiritual successor to scrot — a simplistic CLI-friendly screenshot tool.
ShareX - ShareX is a free and open source program that lets you capture or record any area of your screen...
Snipping Tool - Use Snipping Tool to capture a screen shot, or snip, of any object on your screen, and then annotate, save, or share the image