Greenshot - Greenshot is a free and open source screenshot tool that allows annotation and highlighting using the built-in image editor.
Snip&Sketch - Quickly annotate screenshots, photos and other images with your pen, touch, or mouse and save, paste or share with other apps.
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.
NinjaCapture - All in on Screen Capture
ShareX - ShareX is a free and open source program that lets you capture or record any area of your screen...
Picosmos Tools - Picosmos Tools integrates picture browsing, editing, layout, frames, and cosmetic effects into one set. It also provides plenty of source material.