I can see your local web servers

I started a local webserver listening on localhost:80 just to see what happens, but this thing seems to not detect it. It shows me "Scanning localhost ... localhost complete."

Edit: My guess is that this thing can only detect servers that send a CORS header that permits cross domain access.

It could probably do way better detection if it did not do xhr requests but added script/css/whatever elements to its own page pointing to localhost and detects if those error out.