Freeplane is a free and open-source mind-mapping software available for macOS (and other operating systems). It allows you to create and manage mind maps, concept maps, and other types of diagrams visually, using nodes and branches to represent ideas and their relationships. It[SQ]s known for its flexibility, extensibility (through plugins), and powerful features, despite its lightweight nature. Think of it as a digital whiteboard for brainstorming, project planning, note-taking, and knowledge management.