What does HackerNews think of sliding-panes-obsidian?
Andy Matuschak Mode as a plugin
That said, you can have something identical to this with Obsidian with a few plug-ins and their hosting service.
I also really like Admonition[1] to make styled blocks to format notes. Sliding panes(Andy Matushcak Mode)[2] makes the experience just more natural than windows that need to be resized, etc when switching context.
Found Admonition when learning about Zettelkasten via an efficient video by Artem Kirsanov[3]. Within 17 mins I got the system better than the scary 4 hour overkill vids out there.
[1] https://github.com/valentine195/obsidian-admonition [2] https://github.com/deathau/sliding-panes-obsidian [3] https://www.youtube.com/watch?v=E6ySG7xYgjY&list=PL7eDrfPCCa...
Also see http://fed.wiki.org/view/welcome-visitors and https://github.com/deathau/sliding-panes-obsidian.