NinjaMock

NinjaMock is simple, easy to learn wireframe builder and enables user to create wireframe design efficiently, in a matter of hours. Like other wireframe tools, NinjaMock too has loads of interactive elements which can be used to design mobile app and websites. It is available for all the major platforms such as - IOS, Android and Web. The unique feature NinjaMock has, is its ability to enable creators to collaborate and edit in real-time.

The free version of NinjaMock allows you one project with 200 elements.