Website: https://getsharex.com
Steam store page: http://store.steampowered.com/app/400040
Project page: https://github.com/ShareX/ShareX
Discord server: https://discord.gg/ShareX

ShareX is a free and open source program that lets you capture or record any area of your screen and share it with a single press of a key. It also allows uploading images, text or other types of files to over 80 supported destinations you can choose from.

ShareX website[getsharex.com]
Steam store page
Project page[github.com]