What about Workflowy (https://workflowy.com/)?
It's an interesting project, though, I'll try to check it out and see what I can learn from it.
I use workflowy everyday and it's really cool; it doesn't feel very actively developed though, and that's a shame.
Workflowy is an enlighteningly simple app (it's really just bullet lists with zooming) but it's incredibly effective for what it does, and the free-form nature of it makes it easy to just brain-dump random notes to get your thoughts out into text. I use it to do rubber ducking [1], because just the act of putting my problem into text helps me organize my thoughts. I can't say enough good things about it.
so I have no idea.
There's a screenshot and a live demo. Workflowy is more advanced and capable. I made my app solely to note down everything. I have been using it for 4 solid years now and it has helped me organize my life.