pen.dev is a visual design and prototyping platform integrated directly into integrated development environments (IDEs). It bridges the gap between visual interface design and frontend code, allowing developers to design on a canvas and produce clean code within their editor.
The system provides an interactive canvas that runs inside editors such as VS Code and Cursor, translating visual layouts into structured component code in real time. Continuous synchronization between the canvas and the project repository ensures that visual adjustments map accurately to the underlying codebase.
The tool is designed for frontend developers, software engineers, and product designers collaborating closely with code. Its pricing model is currently free with no paid subscriptions required.