ProjectHuddle - Get design feedback and client approval using WordPress.
Invision - Prototyping and collaboration for design teams
Savahapp - The all-in-one design sharing, collaboration, workflow and app prototyping platform
Marvel - Turn sketches, mockups and designs into web, iPhone, iOS, Android and Apple Watch app prototypes.
Viewflux - Feedback, prototyping and collaboration for designers
UXpin - Design is really about solving problems. UXPin is the UX Design Platform that gets that right.