Responsive Viewer - View multiple screen dimensions in one view
One Click Test - Tool for quickly testing your design layout in one click.
Responsive View - Test your responsive design across different devices
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.
Auto-Layout for Sketch - Responsive design for Sketch
InVision Studio - The world’s most powerful screen design tool