This category mixes wireframing and prototyping apps with mind-mapping tools. Prototyping apps turn screen designs into clickable flows for user testing and developer handoff, while mind maps help outline ideas before writing or planning. Most entries are commercial, and several are web-first services with a desktop app.
Axure RP and Justinmind target detailed interactive prototypes, and Balsamiq produces low-fidelity, sketch-style wireframes. MindNode is a native Mac mind-mapping app. For free options, Pencil is an open source GUI prototyping tool and ExcalidrawZ is a native client for the Excalidraw whiteboard with local files and iCloud sync. Adobe XD is no longer under active development.