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!
Mockuuups Studio - Fast and easy way to create product mockups on macOS, Windows and Linux.
Userbrain - Easy, fast, and affordable user testing for websites and prototypes.
Mediamodifier - Create beautiful designs and product mockups in seconds.
userinput.io - Get on-demand feedback for your app, website or idea. Learn how to improve by hearing real opinions.
mockDrop - Is a webapp for creating free device mockups including your screenshots.