https://en.wikipedia.org/wiki/List_of_concept-_and_mind-mapping_software

https://en.wikipedia.org/wiki/Concept_map

https://en.wikipedia.org/wiki/Mind_map

The software listed on wikipedia all looks pretty old.

Here's one that looks a bit more modern: https://www.mapsofmind.com/

For emacs fans, there's org-brain.

https://github.com/Kungsgeten/org-brain

Check out "Left", distractionless text-based organization software.

https://github.com/hundredrabbits/left

Here's a list of alternative writing software.

https://www.reddit.com/r/writing/comments/6kfd32/a_basic_list_of_different_kinds...