Obsidian

This is useful for study, research, project notes and a reference work of your own. It suits you if your text likes to order by itself. For writing directly together in one shared document, a collaboration tool is often easier. Synchronization and publication are additional choices on top of your local notes.

Create one notebook and first try ordinary notes and links between each other. Insert that folder into your backup before adding a lot of material.

Local Markdown files are not automatically encrypted. Secure your device and storage. Community plug-ins can access files and the Internet; Obsidian cannot reliably limit them to small individual rights. Therefore, keep the limited mode as long as you don't need plug-ins and be selective when you enable them.

Synchronization and publishing via their own services may have been paid. Third-party extensions have access to your notes; choose them consciously.

Synchronization is not a substitute for an independent backup. Check at a service which encryption you choose and save the recovery data. A plug-in can make your note structure dependent on its own operation. Make sure that the core of your information remains understandable as an ordinary text.

Obsidian is especially valuable if you want to connect notes and store information in local Markdown files. You build your own knowledge collection with links between topics. The profit is in those substantive connections, not in an impressive graph. Start simply so that organizing doesn't take more time than writing and finding your notes.

The app fits with information that you want to supplement and connect for a long time. For a simple shopping list, that structure is less important. Also review how your notes, attachments and settings become available on another device. A local file format gives control, but does not take over the choices about synchronization, reserves and extensions.