Right, there're dozens and dozens software to create mockups. Honestly, do you use one of them? Do you really pay for this? Or do you still use the powerful pen and paper?<p>I wonder if a free, powerful, productive tool to make mockups exist. What's your opinion?
Pencil is a free, open source and good prototyping tool.
<a href="http://pencil.evolus.vn/" rel="nofollow">http://pencil.evolus.vn/</a>
It works perfectly on Linux, Mac, and Windows.
It allows you to prototype web apps, iphone apps, and Android apps.