GitMind is a free online mind map maker for brainstorming, project planning, development, action, and other creative tasks. This tool lets you share mind maps with tons of users and collaborate with them. GitMind's mission is to become the leading global platform for digital content in order to enable customers to do their jobs with maximized productivity, little effort and minimal time.
Very good! it has lots of cool styling features, and it's free. It serves ordinary users very well, but it may fall short for professionals.
Free!!! and it does what all the paid ones do plus a nice modern UI as well. It just needs a native Linux client app.