I am looking for a note talking app to keep work notes in. My requirements are:
Allow hierarchical organization of notes (like project1, project1/build, project1/configure) and easy to navigate to different notes.
Allow basic formatting (heading, code block).
Run locally
(Optionally) Have a table of contents for quick navigation
Obsidian looked promising and had the additional benefit of storing notes in Markdown format for easy export. Unfortunately, I would need to buy a commercial license in order to store work-related information.
I have used Zettlr a lot in the past and switched to Obsidian for my general work notes. Both retain the folder structure and would fit your needs for hierarchical organisation. Just load your desired folder as project/vault and you are done.
Obsidian has better backlinks and tagging workflow and a lot of nice plugins for productivity.
Zettlr dev states it is for (academical)writing and therefore will not focus on productivity features.
For Projects I prefer Logseq, as it creates a natural structure very easily and fast. The downside for me is the non standard markdown.