The Pencil Project - Sketching & Prototyping with Firefox 3

The Pencil Project looks like a pretty interesting tool for sketching out and prototyping a site design. It's based on XUL engine in Firefox 3 and looks to be a pretty impressive little open source application. From the Pencil Project website:

The Pencil Project's unique mission is to build a free and opensource tool for making diagrams and GUI prototyping that everyone can use.

Top features:

• Built-in stencils for diagraming and prototyping
• Multi-page document with background page
• On-screen text editing with rich-text supports
• PNG rasterizing
• Undo/redo supports
• Installing user-defined stencils
• Standard drawing operations: aligning, z-ordering, scaling, rotating...
• Cross-platforms
• Adding external objects
• And much more...

Pencil will always be free as it is released under the GPL version 2 and is available for virtually all platforms that Firefox 3 can run. The first version of Pencil is tested against GNU/Linux 2.6 with GTK+, Windows XP and Windows Vista.

Make sure to check out the quick tour/screenshots of the application.

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