OpenToonz - OpenToonz is an animation program that is a free software version of Toonz, the animation software...
Greenshot - Greenshot is a free and open source screenshot tool that allows annotation and highlighting using the built-in image editor.
Synfig Studio - Just another WordPress site
ShareX - ShareX is a free and open source program that lets you capture or record any area of your screen...
Blender - Blender is the open source, cross platform suite of tools for 3D creation.
LightShot - The fastest way to take a customizable screenshot.