Invision - Prototyping and collaboration for design teams
Visily - The easiest and most powerful wireframe software for agile teams.
Marvel - Turn sketches, mockups and designs into web, iPhone, iOS, Android and Apple Watch app prototypes.
Handoff by Marvel - Automatically turn designs into assets, specs and code
UXpin - Design is really about solving problems. UXPin is the UX Design Platform that gets that right.
Zeplin - Collaboration app for UI designers & frontend developers