What do AI crawlers see on your page?
Enter a URL. We compare the HTML a crawler reads with the page a browser renders, and show what disappears without JavaScript.
Checks one public page in about 15 seconds. No signup, nothing stored.
What this checks
Two versions of one page
We fetch the raw HTML the way a crawler does, then render the same URL in headless Chrome and read both with the same parser.
What only JavaScript shows
Text coverage in percent, plus the passages, headings, and internal links that exist only after the scripts ran.
Signals that must not move
Title, description, canonical, robots, and JSON-LD compared side by side, and the HTML size against the 2 MB Googlebot reads.
Content every crawler can read.
We build sites and shops that render on the server, so search engines and AI assistants read the same page your customers see.
Questions about the JavaScript SEO Check
Do AI crawlers run JavaScript?
Mostly not. Vercel's analysis of crawler traffic found that GPTBot, ClaudeBot, PerplexityBot, and the other large AI crawlers fetch JavaScript files but do not execute them. Googlebot renders pages, so Gemini and AI Overviews can see rendered content; ChatGPT, Claude, and Perplexity read the HTML response.
What does the coverage number mean?
The share of words a browser shows that are already in the HTML response, counted word by word regardless of order. Cookie banners are left out of both versions. 90% or more means the page is effectively server-rendered.
Is the 2 MB limit real?
Google's crawler documentation states that for Google Search, Googlebot reads the first 2 MB of an HTML file, measured uncompressed, and indexes only that part. Most pages are far below it; pages with large inline state or SVG sprites can cross it.
My site uses React or Vue. Is that a problem?
Not the framework, the rendering mode. Next.js, Nuxt, Astro, and SvelteKit render on the server by default and score well here. A single-page app that ships an empty <div id="root"> leaves every crawler that skips JavaScript with nothing to read.
Does my browser load the checked page?
No. Our engine fetches and renders the page on its own server and returns only the comparison. Images, video, and fonts are skipped during rendering because they never change the text.
From the blog
- Can AI crawlers read JavaScript?
Mostly not. GPTBot, ClaudeBot, and PerplexityBot read the raw HTML and skip JavaScript. What that hides from ChatGPT and Claude, and how to fix it.
