Gaphor

About

Gaphor is a UML, SysML, RAAML, and C4 modeling application designed to be easy to use while remaining powerful. It implements a fully compliant UML 2 data model, so it goes beyond simple diagram drawing, allowing you to quickly visualize different aspects of a system or build complete, highly complex models. It works on all major platforms, including macOS, and is written in Python and released as 100% open source under the Apache 2 license.

Gaphor suits both casual modelers documenting a project and Model Driven Development experts. Because UML is a graphical language, all information in the model is visible in the diagrams, with no hidden panels or property pages. It supports Class, Interaction, State Machine, Block Definition, and Requirements diagrams, lets you mix diagram items on the same diagram, and offers a built-in styling engine, a tree view for finding model elements, and dark mode. Gaphor is also extensible through plug-ins, such as code generators or documentation exporters, which can be accessed through the GUI or CLI.

For macOS, the simplest way to get Gaphor is to download the official installer. Alternatively, it can be installed with Python's pip tool if the required dependencies are present.