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. The latest stable version of Pencil is 3.1.1 which contains stability fixes and many new features.

Different builds of Pencils are made for popular operating systems. Please select the build on the right side and start installing Pencil.

Stencil collections and Export templates for Pencil can be downloaded separately and installed into Pencil as add-ons.

Pencil provides various built-in shapes collection for drawing different types of user interface ranging from desktop to mobile platforms. Starting from 2.0.2, Pencil is shipped with Android and iOS UI stencils pre-installed.

Stencil Tutorials. This set of tutorials provides you with basic steps to create stencils. The tutorials are organized in topics with sample code included.

JavaScript code in this section will be executed when the collection is loaded into Pencil. In the execution context of these scripts, a special object named collection is available and is virtually bound to the collection itself. This object is also available in the execution of behavior and action code of each stencil so developers can use it ...

Introduction to Pencil Stencil Overview. Pencil controls shapes in its document by mean of stencils. Each stencil (Rectangle, for example) is indeed a template to generate shapes. Each template defines: The look: how the generated shape looks like by mean of SVG elements.

Installing into Pencil as a developer collection. Pencil provides a convenient way to load and reload stencil collection that is under development as it is installed like the others for the testing purpose.

To guarantee the openness of Pencil, licensees are enforced to release modified versions of Pencil in the same terms as defined by the GPL2. This allows community users to benefit from all enhacements made by the others.

To help Stencil developers define how the content in shapes can be changed to be reflect shape's properties, Pencil provides the Behavior concept. With behaviors, attributes or content of the target object can be changed based on Behavior's input values.