Pencil
Pencil 2.0.2 for Windows
Evolus Graphic & Design / Editors
Sketch and draw with this application
Pencil in an open source GUI prototyping and sketching tools, based on Mozilla technologies. This application will help business analysts and developers draw the GUI of applications to prepare proposal documents for clients and to collect requirements.

Software Summary:

You can run Pencil on Windows operating systems. Pencil is a software product developed by Evolus and it is listed in the Graphic & Design category under Editors. Pencil is a free software product listed under The GNU General Public License (GNU GPL or GPL) license which means that it is fully functional for an unlimited time and that you have freedom to run, study, share (copy), and modify the software.

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