Responsive Viewer - View multiple screen dimensions in one view
Rapid Responsive Design - Kill your artboards, design for all sizes faster
Responsinator - Designed to test responsive websites on different devices.
One Click Test - Tool for quickly testing your design layout in one click.
Responsive Website Test - Test any website on desktop, mobile, and tablet
Typewolf - Typewolf helps designers choose the perfect font combination for their next design project—features web fonts in the wild, font recommendations and learning resources.