I have a bit of software that I sell (HTML / JS), that a bunch of people are stealing, simply because beyond obfuscating there's not much I can do to protect it. I've been getting quite good results by tracking these down, and either getting them to buy a license, or enforcing copyright with their hosting provider.
I'd like to get better at finding them.
What I'm doing now is searching for a couple of strings that my HTML shows in <div>s to the user. Mainly error messages. However, I can only find those instances where they haven't changed those very obvious user-viewable strings (which is a problem particularly with people that translate my app, because they find these strings and change them almost every time).
So far the best I've found is to search in URLs, but this doesn't help me unfortunately.