Greenshot - Greenshot is a free and open source screenshot tool that allows annotation and highlighting using the built-in image editor.

MWSnap - MWSnap is basically a free to use Windows snapping tools that are used for snapping any part of the screen that is currently displaying on the front of all opened programs and windows.

Swiftdrop - Swiftdrop is a super simple cloud sharing app for Mac.

ScreenTray - A better way to capture, annotate and share screenshots

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

LightShot - The fastest way to take a customizable screenshot.