Nulis is an open source tree editor for writers, inspired by Gingko.
Nulis allows you to represent any information as trees, beginning with abstract ideas and refining them by adding nested cards that contain more details. This format is very useful for writing stories, articles, outlining courses, GTD, and many other purposes. I think that organizing your creative projects in such way is an incredibly powerful idea, and I want more people to be able to apply use it in their own process.
I built Nulis with Node/React/Redux, so that many developers would be able to understand the code and easily customize it for their own purposes.
I hope that you will find it useful, as a writing tool, or just as an example of building a pretty cool SaaS with this tech =)