ShareX - ShareX is a free and open source program that lets you capture or record any area of your screen...
Greenshot - Greenshot is a free and open source screenshot tool that allows annotation and highlighting using the built-in image editor.
LICEcap - A straightforward, high performance application that enables users to capture a portion of the desktop and save it to . GIF or . LCF, LICEcap is available for download as a GPL free software.
Shutter - Shutter is a feature-rich screenshot program.
Snagit - Screen Capture Software for Windows and Mac
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