POP (Prototyping on Paper) - POP helps you make interactive prototype with ease. If you can draw, you can design apps.
UserTesting.com - Usability testing has never been easier. Get videos of real people speaking their thoughts as they use websites, mobile apps, prototypes and more!
Marvel - Turn sketches, mockups and designs into web, iPhone, iOS, Android and Apple Watch app prototypes.
UserZoom - Test, measure, and monitor UX with our cost-effective all-in-one platform. UserZoom is a cloud-based solution for online usability testing.
BluePrint UI design - Blueprint is an UI design application for iPad and iPhone
Hotjar - The #1 Leader in Heatmaps, Recordings, Surveys & More. Sign up for a 15-day free trial and start learning from real user behavior today!