Instabug - The top apps in the world rely on Instabug for beta testing, user engagement and crash reporting.
Twitterfeedback.app - Discover user feedback from Twitter for free
UserTest.io - User testing made simple. High-quality, affordable user testing solutions from real users, here in the UK. Improve your usability!
Canny - Canny helps you collect and organize feature requests to better understand customer needs and prioritize your roadmap.
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!
Userbrain - Easy, fast, and affordable user testing for websites and prototypes.