https://www.freetech4teachers.com/2021/08/fifteen-tools-for-creating-mind-maps.html

GitMind  more than one hundred templates

Forky is simple but effective a free mind mapping tool

Whimsical is a good tool for creating flowcharts, mind maps, Venn diagrams, and a variety of other charts and diagrams.

Transno is a service that lets you write notes and outlines that can then be turned into mind maps and flowcharts with just one click.

Bubbl.us is a mind mapping and flowchart tool

MindMup is a mind mapping tool that can be used online, with Google Drive, and on your desktop.

Coggle is a collaborative mind-mapping service

Spider Scribe is an online mind map creation service.

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more on mind maps in this IMS blog
https://blog.stcloudstate.edu/ims?s=mind+map