Graphical User Interface (GUI) prototyping tool that allows users to create diagrams, UI mockups, and wireframes. It is designed to be simple and lightweight, making it suitable for quickly sketching out ideas for software interfaces, websites, or mobile applications. Pencil provides a wide range of built-in shapes, stencils, and templates to facilitate the prototyping process, supporting various platforms including Windows, macOS, and Linux.
Alternative: Sketch, Adobe XD, Axure RP.