UXPin is a collaborative design platform, allowing entire teams to participate in the design process from start to finish.

Fluid UI is a browser-based wireframing and prototyping tool developed by Fluid Software and used to design mobile touch interfaces.

Ext JS is a pure JavaScript application framework for building interactive cross platform web applications.

Pidoco is a cloud-based collaboration software.

Antetype is a design and layout software focused on visual design. It saves you a lot of time creating and optimizing UIs.

Storyboard That is a free online storyboard creator.

Mockup Designer is an online mockup creator.