ShareX

ShareX is an open source image capture and manipulation app that is both lightweight and feature rich. The app has an easy to operate user interface and has lots of features

ShareX lets you capture screens/app windows in a number of different shapes with short-cut keys. The app internally uses Greenshot image editor to annotate the images you take. ShareX lets you crop or blur/obfuscate the images, but the really cool feature of ShareX is the ability to automatically upload images to your favourite image host such as Imgur, Flickr, Picassa, Tinypic or Imageshack. You can even use a custom up-loader

The really great thing about ShareX is that almost all aspects of the app are configurable. You can choose short-cut keys to automatically take screenshots of entire screens or part of the screen. You can upload images to different image hosts or a custom up-loader. Overall, ShareX is a great, lightweight tool that does the job properly with numerous configurable options