It's not open source and one-time payment, but I'm working on Cozy, which basically works like Obsidian. I don't use a server, so I can't see your entries. I also don't track anything apart from crashes, but you can disable this option too. If you'd like to try it out, let me know!
Disclaimer: I am the developer behind this app.
It's not open source and one-time payment, but I'm working on Cozy, which basically works like Obsidian. I don't use a server, so I can't see your entries. I also don't track anything apart from crashes, but you can disable this option too. If you'd like to try it out, let me know!