Your notepad is created the moment you start typing, and every change saves itself. There’s nothing to sign up for.
Two links, your choice
Send the edit link to people you want writing with you, and their changes appear as they type. Send the view-only link to everyone else.
Keep your links safe
Without an account, the link is the only way in. If you lose it, we can’t get it back for you. Your browser remembers your recent notepads under “My notepads”.