What is the web address for Arthur Christmas naughty or nice detector?

There is no official "Arthur Christmas naughty or nice detector" website. The film "Arthur Christmas" is a fictional story and does not have a real-life online counterpart for determining if someone is naughty or nice.

It's important to remember that the concept of "naughty or nice" is a fictional idea within the context of the film, and there's no actual way to determine someone's behavior in such a simplistic way.