Linked Ideas - A macOS/iOS apps to treat ideas as links of concepts.
Source Wireframe Kit - Library of 537 blocks for desktop and mobile prototyping
Freeplane - Freeplane is a powerful and free software for building mind maps.
Contra Wireframe Kit - Open source wireframe kit for design and prototyping 🚀
vym - VYM (View Your Mind) is a tool to generate and manipulate maps which show your thoughts.
Platforma - Wireframe library of layouts and UI elements