Mockplus is a desktop based prototype tool aimed at rapid prototyping.
Sketch is a popular tool for web and app design. It has the best features from Photoshop and Illustrator packed into one without the fluff.
Invision is a prototyping platform built for designers. It allows designers to quickly create animated and interactive mockups.
Pixate is an Accel-funded Y Combinator alum. It's initial focus was to allow developers to style native applications using CSS. Nowadays, it has a much broader approach. It g...