Freeplane began as a fork of the Freemind project. While maintaining comparability with Freemind file format, it has far outpaced in features and development. As of 3/5/2022, the latest Freeplane update (1.9.3) is 3/5/2022 vs Freemind was last updated (1.0.1) 2/5/2016. Active, helpful community.
Xmind - Xmind is a brainstorming and mind mapping application.
Markdown Viewer - Markdown document viewer. Allows to visualize formatted markdown documents in browser.
FreeMind - FreeMind is a premier free mind-mapping software written in Java.
Markdown Preview for (Neo)vim - Preview markdown on your modern browser with synchronized scrolling and flexible configuration.
vym - VYM (View Your Mind) is a tool to generate and manipulate maps which show your thoughts.
Joplin - Joplin is a free, open source note taking and to-do application, which can handle a large number of notes organised into notebooks. The notes are searchable, tagged and modified either from the applications directly or from your own text editor.