Do AI crawlers render JavaScript?
Google's and Microsoft's crawlers do, and Apple's may. OpenAI, Anthropic and Perplexity don't say, and Vercel's 2024 study of their crawlers' traffic found none of them running JavaScript. Put the text that matters in the HTML your server sends.
Checked against each vendor's own docs on October 8, 2026.
What each crawler does with JavaScript.
Google and Microsoft document that their crawlers render JavaScript, Apple that its crawler may, and Common Crawl that its crawler doesn't. The AI companies say nothing, and Vercel's 2024 study of their crawlers' traffic fills the gap.
GooglebotRenders
Google Search, which AI Overviews and AI Mode draw on, runs your JavaScript in an evergreen Chromium before it indexes the page. It won't render scripts that robots.txt blocks.[1, 2]
BingbotRenders
Bing renders pages with the current Microsoft Edge, and still lists hiding critical content behind client-side rendering as a practice to avoid.[3, 4]
ApplebotMay render
Apple says Applebot may render your pages in a browser, and warns against blocking the JavaScript and CSS it needs.[5]
CCBotDoesn't render
Common Crawl says it doesn't execute JavaScript.[6]
GPTBot, OAI-SearchBot, ChatGPT-UserDidn't in a 2024 study
OpenAI's crawler page says nothing about JavaScript. Vercel's study of AI crawlers' traffic found OpenAI's fetching JavaScript files, in 11.5% of ChatGPT's requests, without running them.[7, 8]
ClaudeBotDidn't in a 2024 study
Anthropic's crawler page says nothing about it, and its developer web fetch tool doesn't support pages rendered with JavaScript. The same study found ClaudeBot fetching JavaScript files in 23.8% of its requests without running them; Claude-SearchBot and Claude-User weren't in it.[8, 9, 10]
PerplexityBotDidn't in a 2024 study
Perplexity's crawler page says nothing about it, and the study found PerplexityBot not running JavaScript either. Perplexity-User wasn't in it.[8, 11]
meta-externalagent, BytespiderDidn't in a 2024 study
Meta's and ByteDance's crawlers didn't run JavaScript in the study either; neither company documents it.[8, 12]
Cited pages put their words in the HTML.
We loaded cited pages in Chrome and compared what a visitor sees with the HTML the server sent, using the X-ray's own rendering check.
of 2,022 cited pages show at least 99.5% of their main text in the HTML the server sends, where a crawler that skips JavaScript can read it.
show more than 40% of their text only after JavaScript runs: 55 pages.
of the 473 pages only Google's AI cited need JavaScript for most of their text, against 2.2% of the 1,304 pages only ChatGPT, Claude or Perplexity cited. Google renders; the 90% ranges overlap slightly, so read it as a lean.
Blue: Google's AI, whose crawler renders JavaScript. With 209 to 771 pages each, most of these bars' 90% ranges overlap.
Send the words in the HTML.
Render on the server
Server-side rendering or static generation, as Next.js, Nuxt, Astro and SvelteKit do, puts the text in the first response. Google still recommends it: it's faster for users and crawlers, and not all bots run JavaScript.[1]
Prerender a single-page app
If the app has to stay client-side, serve a prerendered HTML copy of each page that matters: pricing, product, docs.
Keep links and structured data in the HTML
JSON-LD a script injects, and links a script builds, reach only crawlers that render.
Don't block your scripts
Google won't render JavaScript from files robots.txt blocks, and Apple warns about blocked JavaScript and CSS.[1, 5]
Look at the raw HTML
Run
curl https://example.com/pageor view the page's source, and search for a sentence you can see on it. If it isn't there, crawlers that skip JavaScript don't see it.
See what your pages show without JavaScript.
The free JavaScript rendering checker renders your homepage and up to 3 key pages in a browser and shows how much of their text only appears after scripts run, passage by passage.
Questions about JavaScript and AI crawlers.
Does ChatGPT see content loaded by JavaScript?
Probably not. OpenAI doesn't document it, and Vercel's 2024 study of its crawlers' traffic found them fetching JavaScript files without running them. Put the text in the HTML your server sends.
Does Google render JavaScript for AI Overviews?
Google Search renders pages with JavaScript before it indexes them, and AI Overviews and AI Mode show pages from that index. Google documents no separate rendering step for them.
Do I need server-side rendering for AI search?
It's the safe choice for every crawler. Google and Bing render JavaScript and Apple may, yet Google still recommends server-side or pre-rendering because not all bots run it, and Bing lists hiding critical content behind client-side rendering as a practice to avoid. Nothing published shows ChatGPT's, Claude's or Perplexity's crawlers running JavaScript.
How much of a page can depend on JavaScript?
GEOFast's rendering checker warns when more than 10% of a page's text appears only after JavaScript runs, and fails it above 40%. Of the cited pages we tested, 87.0% showed at least 99.5% of their main text without it.
Do AI crawlers read JSON-LD that JavaScript adds?
Only the ones that render. Put structured data in the HTML your server sends, where every crawler finds it.
Where each fact comes from.
Each numbered source is the page a fact comes from, most of them the vendor's own documentation, read on October 8, 2026. The answers above repeat facts marked in the guide. Vendors change these pages, so check them before you act.
- 1Google: Understand JavaScript SEO Basicsdevelopers.google.com/search/docs/crawling-indexing/javascript/javascript-seo-basics
- 2Google: AI Features and Your Websitedevelopers.google.com/search/docs/appearance/ai-features
- 3Microsoft: The new evergreen Bingbot simplifying SEO by leveraging Microsoft Edgeblogs.bing.com/webmaster/2019/10/The-new-evergreen-Bingbot-simplifying-SEO-by-leveraging-Microsoft-Edge/
- 4Microsoft: Bing Webmaster Guidelinesbing.com/webmasters/help/webmaster-guidelines-30fba23a
- 5Apple: About Applebotsupport.apple.com/en-us/119829
- 6Common Crawl: FAQcommoncrawl.org/faq
- 7OpenAI: Overview of OpenAI Crawlersdevelopers.openai.com/api/docs/bots
- 8Vercel: The rise of the AI crawlervercel.com/blog/the-rise-of-the-ai-crawler
- 9Anthropic: Does Anthropic crawl data from the web, and how can site owners block the crawler?support.claude.com/en/articles/8896518-does-anthropic-crawl-data-from-the-web-and-how-can-site-owners-block-the-crawler
- 10Anthropic: Web fetch toolplatform.claude.com/docs/en/agents-and-tools/tool-use/web-fetch-tool
- 11Perplexity: Perplexity Crawlersdocs.perplexity.ai/docs/resources/perplexity-crawlers
- 12Meta: Meta web crawlersdevelopers.facebook.com/documentation/sharing/webmasters/web-crawlers
Keep reading
- The free JavaScript rendering checkerSee how much of your pages AI crawlers miss because it only appears after JavaScript runs. GEOFast renders your key pages and compares. Free, no sign-up.
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- AEO vs GEO vs SEOAEO vs GEO vs SEO: where each name came from, what Google and Microsoft say, the work all three share, and the four things that change with AI answers.
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- Does ChatGPT use Google or Bing?What OpenAI documents about where ChatGPT search gets results (Bing, its own crawler and index), what is only reported about Google, and what it means for you.
- Rank in Google's AI OverviewsWhat Google says you need to show up in AI Overviews, how query fan-out and nosnippet work, and what studies show: 38% of cited pages rank in the top 10.
- Rank in Google AI ModeWhat sets Google's AI Mode apart from AI Overviews: query fan-out, follow-ups, a custom Gemini and Search Console's counts, and how often the two cite one page.
- Perplexity SEOHow Perplexity finds, reads and cites pages: its two crawlers, what its docs say and leave out, the Cloudflare dispute, studies, and what our runs show.
- Which AI crawlers to allowWhich AI crawlers feed ChatGPT, Claude, Perplexity and Google's answers, which only train models, and what the 1,529 of 1,605 cited sites we could read allow.
- robots.txt for AI crawlersCopy-ready robots.txt rules that keep AI search crawlers in and training crawlers out, how each crawler reads the file, and the mistakes that lock AI out.
- What is llms.txt?llms.txt is a Markdown file that tells AI agents what a site holds. Its format, a real example, who reads it today, and what studies show about its effect.
- Firewalls that block AI crawlersCloudflare, Vercel, AWS WAF and others can turn AI crawlers away even when robots.txt lets them in. Where each setting lives and how to let crawlers through.
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