Where are my notes stored?
Your notes are currently stored in a cloud database. All notes are encrypted by default and can only be decrypted by the note owner and those they have granted access. The developer of DECK does not have any ability to read your notes.
DECK is experimental software, so for peace of mind you might want to take regular backups of your notes. You can do this by using the "Export" / "Export All" functionality in the note header menu.
Where can I see the code?