Free, open source, lightweight and no advertisements. I’ve been using this for couple of months now and it’s an amazing tool – not only for screenshots but videos and files too.
Just integrate it with your FTP, Google Drive, DropBox, imgur or any other service available, send your file and after that the app will automatically copy a link to the file for you, just paste it to your friends and that’s it! Just wanted to spread the love.
You can download it here.