Is it AI? Looking for evidence instead of guessing

People ask me all the time whether a site or a product was built with AI. Most detectors answer with a guess about writing style. I wanted something that looks for evidence you can point at.

Is it AI? checks the page you're on and answers in one word, AI, Human or Mixed. Behind that word is everything it found. Agent instruction files served by the site, builder badges, generator metadata, content credentials on images, configuration left in source maps, and commit trailers in a linked repository.

Showing the work

Every finding says what it is and how much it's worth. Direct evidence is kept apart from a signature that merely suggests. The stack counts too. A site on the newest framework releases with stock photos looks like what AI builders produce by default. A site with years of accumulated marketing tools looks like neither.

Age counts as well. A page published before ChatGPT made AI writing common is evidence on its own.

Verdicts can be wrong, so they can be argued with. You can correct one on the spot, and the correction stays in your browser.

Written by people, flagged as AI

The humbling moment came early. Several of thoughtbot's own blog posts, written by people years ago, read as AI because they used words detectors associate with models. That's the problem with judging style. People wrote that way first.

I capped how much vocabulary could count, and now the things you can point at always outweigh writing habits.

Tools aren't authors

The honest limit is that evidence of a tool isn't evidence of authorship. An agent file shows an AI coding tool was used on the project. It doesn't show that the tool wrote the page you're reading, and the wording says so throughout. Whether that distinction survives contact with real readers is the thing I most want to find out.