MockFlow is an online wireframe tool for software and websites.

Justinmind is a powerful wireframe software to define web and mobile applications.

Mockingbird helps you you create and share clickable wireframes. Use it to make mockups of your website or application in minutes.

Moqups is a stunning HTML5 App for creating high fidelity SVG mockups, wireframes and clickable prototypes

Concept.ly helps you Share, Annotate and Get Valuable Feedback Faster

Creately helps you easily draw diagrams online using it's online diagramming tool.

Flinto makes it quick and easy to create prototypes that look just like the real thing.

Gliffy.com is a web-based diagram editor.It helps create and share flowcharts, network diagrams, floor plans, user interface designs and other drawings online.

Lucidchart is your solution for visual communication like online flowcharts, diagrams, UML sketches, and ER models.