Protowire

Protowire was a prototyping plugin for Sketch which is a UI design application. At the time Sketch didn't have prototyping. It allowed you to create screen transitions between artboards, overlays, animate layers and scrollable regions. You could also create interactive components like buttons that had a hover effect. The generated prototypes consisted of SVG and a JavaScript layout engine that made use of Sketch's resizing constraints and artboard groups to adapt to any screen size. So you could make a prototype that worked on smartphones and tablets. The prototypes could be shared on the web and had a router so individual screens could be linked to.