Marvel - Turn sketches, mockups and designs into web, iPhone, iOS, Android and Apple Watch app prototypes.
Envisage - Inject contextual help on your site. Point and click style.
Ditto for Developers - Sync the latest copy edits from design to development
Codesign.io - Visual feedback on everything
Kite Compositor - A powerful animation and prototyping application for Mac & iOS.
Product Fit - Measure product/market fit in app with your users.