I would like to build something like http://isthissitebuiltwithdrupal.com/ or http://whatcms.org/, both to make it easier for us to validate sites, and also because it's cool.

A note: if someone wants to tackle this, it is related to Made with Wagtail but I don't think it should be built within it. MWW could potentially integrate with that thing though.

At the moment we use https://wappalyzer.com/, which detects Django / Python, but not with a great degree of confidence IIRC.

Here are the heuristics I could think of, in no particular order:

• Determine if the site is built with Django. See https://stackoverflow.com/questions/721934/how-can-you-tell-if-a-site-has-been-made-with-django (that's a start)
• Check if the site uses a Wagtail badge (https://wagtail.io/wagtail-badges/) (not too frequently used)
• Load /admin/login and check for "wagtail" in the response (either in the page title, or wagtailadmin JS file – that's a 100% tell I think).
• Sites have their admin/login protected by basic auth or obscured, so also look at /robots.txt and follow the links? Seems a bit evil.
• See what the checks for other popular Django-based CMSes are?
• Check if the site is open-source (has a GitHub ribbon / badge / link, then check if the requirements.txt in the GitHub repo have wagtail in them. (Pretty convoluted)
• Detect clues exposed by third-party Wagtail apps (https://github.com/springload/awesome-wagtail)