Padlet - Visual boards for organizing anything.
Freeplane - Freeplane is a powerful and free software for building mind maps.
Kids A-Z - Kids A-Z created and published by Lazel Inc.
vym - VYM (View Your Mind) is a tool to generate and manipulate maps which show your thoughts.
Quizalize - Quizalize is a leading web-based and mobile-based classroom application that delivers the best and easiest way to differentiates your teaching.
Linked Ideas - A macOS/iOS apps to treat ideas as links of concepts.