If at all you could make it stateless, you should. For one, you don't need a db. Also, there were some people in the thread that liked the local storage feature. Finally, as a user, I can feel safe using your service because I know at any time, if you site disappears, I have the url and I can trivially parse the url into json and do whatever I want with it. You could even build the parser or have an export to json button.

If you want to add more stuff like images, longer descriptions, some links, etc, then yeah you'll likely need a backend