Mockup.io!

Free web and mobile mockup tool.Transform your design and mockups into clickable interactive applications. Perfect way to validate ideas faster with lean startup thinking.

Origami Studio is a free design tool built by Facebook designers for creating interactive UI prototypes. An elegant, layer-based interface allows designers to repaidly create prototypes with layers, build interactions and then share them with others.

Principle makes it easy to create animated and interactive user interface designs. Whether you're designing the flow of a multi-screen app, or new interactions and animations, Principle lets you create designs that look and feel amazing.

Fluid UI is the fastest mobile app prototyping tool available. Design and test your low and high fidelity app mockups on a mobile device with ease. Simple and UX oriented, this UI tool helps unlock creativity and will save your team time and money while gathering app requirements.

Comp CC makes it easy for designers to lay out ideas with real assets like photos, text and shapes. They can then send the wireframe to Photoshop CC, Illustrator CC, InDesign CC or Muse CC to refine and finish.

Upload your designs,mockups or wireframes by file or by URL snapshot, organize them and connect them to web prototypes. Share them with friends, colleagues and clients to get point specific Feedback. Giving Design Feedback is also possible without any registration.