ShareX - ShareX is a free and open source program that lets you capture or record any area of your screen...
Xnapper - Take beautiful screenshots instantly
Greenshot - Greenshot is a free and open source screenshot tool that allows annotation and highlighting using the built-in image editor.
TakeaScreen - Take & capture screenshots like a Pro!
LightShot - The fastest way to take a customizable screenshot.
Shottr - Shottr is a free macOS screenshot app with scrolling screenshots, OCR, annotation and measurement instruments.