DevDocs - Open source API documentation browser with instant fuzzy search, offline mode, keyboard shortcuts, and more

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

Zeal - Zeal is an API Documentation Browser.

Shutter - Shutter is a feature-rich screenshot program.

Loom - Loom is a screen recording extension for Chrome that gives people the ability to create and share media. Create your own videos using your camera, screen view, and audio. Read more about Loom.

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