UXpin - Design is really about solving problems. UXPin is the UX Design Platform that gets that right.
Figma - Team-based interface design, Figma lets you collaborate on designs in real time.
Moqups - The most stunning HTML5 app for creating resolution-independent SVG mockups, wireframes & interactive prototypes for your next project
Sketch - Professional digital design for Mac.
Axure RP - The prototyping and specification software used by 87% of the Fortune 100. Beyond mockups, design interactive prototypes for business solutions, websites, and applications.
Invision - Prototyping and collaboration for design teams