Figma - Team-based interface design, Figma lets you collaborate on designs in real time.
Iceberger - Draw an iceberg and see how it will float
Teampaper Snap - Take a snapshot, highlight key areas and share feedback
Stickman Builder - Free parametric graphic Stickman Builder, creates fascinating stick figures on the fly.
Inspect by InVision - A magical new design to development workflow from InVision
Drawy - Learn to draw, use camera to score your drawings