Invision - Prototyping and collaboration for design teams
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
Zeplin - Collaboration app for UI designers & frontend developers
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
ProtoPie - ProtoPie is the easiest tool used to turn your UI/UX design ideas into highly interactive prototypes for mobile, desktop, web, all the way to IoT.