Invision - Prototyping and collaboration for design teams
Zeplin - Collaboration app for UI designers & frontend developers
Balsamiq - Balsamiq. Rapid, effective and fun wireframing software.
Moqups - The most stunning HTML5 app for creating resolution-independent SVG mockups, wireframes & interactive prototypes for your next project
Axure - The most powerful way to plan, prototype and hand off to developers, all without code. Download a free trial and see why professionals choose Axure RP 9.
Fluid UI - Fluid UI helps you prototype Android, iPhone, iPad or Windows 8 mobile apps with our custom libraries, or upload your own images for pixel perfect mobile