Pencil Project is a free open-source wireframing and GUI prototyping tool from Evolus. Compare its features, pricing and alternatives like Balsamiq.
Pencil Project is a free, open-source desktop application for sketching GUI mockups, wireframes and simple diagrams. Built by Evolus, a software company based in Ho Chi Minh City, Vietnam, it began life in 2008 as a Firefox-based sketching tool before becoming a standalone Electron desktop app in its version 3 rewrite.
The tool is aimed at anyone who needs to quickly rough out an interface or flow, from students and hobbyists to small development teams, without paying for software or creating an online account. It runs on Windows, macOS and Linux.
Pencil ships with built-in shape and UI-control stencils covering desktop, web and mobile interface elements, plus general diagramming shapes for flowcharts and basic diagrams. Users can build multi-page documents and link pages together to create simple clickable prototypes.
The version 3 file format is zip-based, which improves handling of large documents and embedded bitmap assets compared with the original XML-based format, and the app supports importing additional stencil collections, including OpenClipArt-based shape libraries, to extend its default toolset.
Pencil Project is completely free and released under the GNU General Public License v2 or later, with no paid tiers, subscriptions or enterprise licensing offered by Evolus.
Because there is no commercial edition, all users get the same feature set regardless of use case, and the software can be freely redistributed or modified under the terms of the GPL.
Yes, Pencil Project is completely free and open source under the GNU GPL v2 or later license, with no paid tiers.
Pencil Project runs on Windows, macOS and Linux as a native desktop application built on Electron.
Pencil Project is developed by Evolus, a software company based in Ho Chi Minh City, Vietnam.
Pencil supports basic interactive prototyping by linking pages together to simulate simple navigation flows, though it lacks the advanced interaction features of modern prototyping tools.
Pencil is an offline desktop app with a simpler, low-fidelity sketching toolset, while Figma and Penpot are cloud-based platforms with real-time collaboration, component systems and richer prototyping.
Since version 3, Pencil uses a zip-based file format designed to better handle large documents and embedded bitmap assets.
The most recent stable release, version 3.1.1, shipped in January 2023; the project has had periods of slower development but remains available as open-source software.
Yes, users can import additional stencil collections, including OpenClipArt-based shape libraries, to extend the default toolset.