I wrote my own note sharing app using free Claude. It's self-hosted, allows for non-simultaneous editing by multiple users (uses locks), it has no passwords on users, it shows all notes in a list. Very simple app, over all. It's one Go file and one HTML file. I like it, it's exactly what I want for sharing notes like shopping and todo lists with my partner.
The AI wouldn't have been able to do it by itself, but I wouldn't have been arsed to do it alone either.