Raindrop.io - All your articles, photos, video & content from web & apps in one place.
ScreenTray - A better way to capture, annotate and share screenshots
Tagpacker - A free tool to quickly collect, organize, and share your favorite links.
Annotate by Convergely - Easily annotate images you get on Slack - just like Skitch
Greenshot - Greenshot is a free and open source screenshot tool that allows annotation and highlighting using the built-in image editor.
Weava - Workspace to highlight, organize & collaborate on your research articles.