Why crawlers can't see JavaScript sites
Published · Last updated
As of October 2026, the four AI crawlers we test most (GPTBot, ClaudeBot, PerplexityBot and CCBot) read the HTML your server sends and do not run JavaScript. If your site builds its pages in the browser, those crawlers get an empty shell and your product never enters their answers.
What is happening
Sites made with AI app builders and many modern frameworks send a near-empty HTML file, then use JavaScript to draw the page. A person's browser runs that script and sees a full page. A crawler that skips the script sees a blank div and a script tag.
Why it matters
AI assistants can only cite what they could read. A page that is invisible at crawl time is invisible when someone asks "what's the best tool for X?"
See it yourself
Open your page, choose View Source (not Inspect), and look for your headline and main paragraph. If they are not in that raw HTML, most AI crawlers cannot see them either.
What this does not tell you
Which of your pages are affected, whether a prerender service covers every bot or only some, and what to change first. That depends on your platform and setup.