pencil
An open-source diagramming and GUI prototyping tool built on Electron for creating diagrams and mockups.
What is pencil?
Pencil is an open-source diagramming and GUI prototyping tool that enables users to create diagrams, wireframes, and mockups. It is built on Electron for cross-platform compatibility and addresses performance and scalability issues found in earlier versions. The tool supports features like custom font embedding, tree-like page management, and improved PDF export.
Designers, developers, and technical writers who need a free, open-source tool for creating diagrams and GUI prototypes without relying on proprietary software.
Pencil offers a completely free and open-source alternative to commercial diagramming tools, with a focus on community contributions, cross-platform support via Electron, and scalable document management for large projects.
Overview
The Pencil Project's unique mission is to build a free and opensource tool for making diagrams and GUI prototyping that everyone can use.
Use Cases
Best For
- Creating wireframes and mockups for software interfaces
- Designing flowcharts and process diagrams
- Prototyping GUI layouts for applications
- Generating diagrams for technical documentation
- Embedding custom fonts and resources in design documents
- Exporting designs to PDF for sharing and printing
Not Ideal For
- Teams requiring real-time, cloud-based collaboration features
- Projects needing interactive, clickable prototypes with animations
- Enterprises seeking vendor support and service-level agreements
- Users on older operating systems like Windows XP or OS X 10.8 and below
Pros & Cons
Pros
Built on Electron, Pencil runs seamlessly on OS X 10.9+, Windows 7+, and Linux distributions like Ubuntu and Fedora, ensuring wide accessibility.
The tree-like page model reduces memory usage for large documents, allowing better organization and performance with complex projects.
Supports embedding custom fonts and bitmaps directly into .epz files using a zip-based format, ensuring consistent typography and resource management.
As a completely free alternative to proprietary tools, it encourages community contributions and avoids licensing costs, aligning with its open-source philosophy.
Cons
Pencil V3 is under heavy development with GA builds expected in June, so it may have bugs, incomplete features, or breaking changes.
Requires cloning the repository, checking out the development branch, and using npm to install dependencies, which is more involved than a simple installer.
Compared to established tools like Figma, it lacks a robust plugin ecosystem and API support for seamless integration with other design or development workflows.
Open Source Alternative To
pencil is an open-source alternative to the following products:
Axure is a wireframing and prototyping tool used by UX designers and product managers to create interactive prototypes, wireframes, and documentation for web and mobile applications.
A rapid wireframing tool that helps designers and developers create mockups and prototypes with a hand-drawn, sketch-like appearance.
A diagramming and vector graphics application from Microsoft used to create flowcharts, organizational charts, network diagrams, and other visual representations.
Frequently Asked Questions
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