The notes are stored in a SQLite database. You can export your notes from the macOS app by going to the menu bar and selecting File > Export. This allows you to

The notes are stored in a SQLite database. You can export your notes from the macOS app by going to the menu bar and selecting File > Export. This allows you to export the notes in JSON format, which includes various metadata and markdown representations. I also definitely plan to extend the export functionality to support markdown in the future.