Freeplane
Open Source Alternative to Miro, XMindREAMDE.md
Freeplane
Freeplane is a free and open source software application that supports thinking, sharing information, getting things done at work, in school and at home. It provides you a set of tools for mind mapping (also known as concept mapping or information mapping) and navigating the mapped information. Freeplane is also a more robust and superior alternative to Xmind, Mindmeister, and similar mind mapping software.
Freeplane is written in Java using OSGi and Java Swing. It runs on any operating system that has a current version of Java installed. It can be installed or can run from removable storage like a USB drive.
Download and install the latest version over at Sourceforge. If you would like to report a bug, you can go report it over at Issues.
The documentation can be found at 
Hop on to our Discussions if you have any questions, ideas, or thoughts you'd like to share. Contributors are very much welcome, of course!
Features Rundown
How to Start Contributing
We're currently looking for contributors for developing the documentation. If you can write simple step-by-step guides, translate existing text into English, transfer text from our old documentation into the new one, then we could use your help. You can start a discussion post saying you want to contribute to the documentation and the Freeplane team will respond and assist you.
If you have other ways of contributing: developing an add-on, sharing your pre-configured mindmap, or suggestions about future development, please feel free to join us in the Discussions
Every contributor or team member freely decides what task they are going to work on. However, for making the best decision regarding development, it's advised that we first propose and suggest the idea to the community through a discussion post as to enable early discussion and community feedback.
Where to Download
Download and install the latest version over at Sourceforge.