Pencil

About: An open-source GUI prototyping tool that's available for ALL platforms.Pencil is built for the purpose of providing a free and open-source GUI prototyping tool that people can easily install and use to create mockups in popular desktop platforms.

Features:

-Easy GUI Prototyping

-Built-in Shape Collections

-Diagram Drawing Support

-Exporting to Different Output Formats

-Easily Find Cliparts from the Internet

-Inter-page linking

DOWNLOAD