Extra: Digital prototyping shortcuts

If you want to turn your sketch or image into an interactive prototype of an iPhone or Android app you cannot go wrong with POP by Marvel.
Turn a paper sketch into a clickable prototype with POP by marvel
It allows you to sketch your interface on a piece of paper, take a picture with their software and add clickable areas that link to different pages. For the test user, the interface will feel like a sketch version of your app mimicking what would happen if you click links and buttons on the page.