Pen

Pen is an AI-powered design editor that combines a visual canvas with coding workflows. It allows designers and developers to create websites, application interfaces, presentations, and other visual content. Users can manually edit layouts or ask AI agents to generate and modify individual elements, screens, and complete flows. Its canvas supports reusable components, design systems, and precise layout controls. Integration with IDEs and external agents through MCP enables design operations directly from development tools. Designs are stored in an open, JSON-based .pen format that can be versioned with Git. Figma designs and existing web pages can be imported as editable elements. Export options include HTML, CSS, Tailwind, and image formats. Pen is the successor to Pencil and supports Windows, macOS, and Linux.