Which AI Crawlers Can Access Your Website? A Guide to AI Crawler Access

AI Crawler Access describes whether automated systems from companies like OpenAI, Anthropic and Perplexity are allowed to reach and read your web pages. You control it through your robots.txt file, server-level rules, your CDN and any security tools in front of your site. The right setting is a deliberate choice, not a default you inherited.

We work on AI visibility every day at Grid13, and the single most common thing we see is a company that has no idea which bots it lets in. Not a bad policy — no policy. This guide gives you a method to check it this week and decide on purpose.

What is AI Crawler Access, and why should a marketing lead care?

Two different jobs are hiding under one term, and confusing them causes most of the bad decisions we see.

The first job is training: a bot reads your content to help build or refine a model. The second is retrieval: a bot fetches your page in real time because a user asked a question and the AI wants a current source to cite. These are separate crawlers with separate names, and you can allow one while blocking the other.

The traffic is no longer a rounding error. According to Senthor's State of AI Bots report, AI bots made up 31.5% of web traffic in Q3 2025 — roughly 46 AI requests for every 100 human visits. If you have never looked at who those bots are, a third of what hits your server is a mystery to you.

Which AI crawler bots should you actually know?

You do not need to memorize a hundred user-agents. A handful account for nearly all the volume that matters, and they split cleanly by purpose.

• GPTBot — OpenAI's training crawler. Blocking it keeps your content out of future model training but does not affect ChatGPT's live browsing.
• ChatGPT-User — OpenAI's retrieval crawler. It fetches pages when a user's prompt triggers a live lookup. This is the one that can lead to a citation.
• ClaudeBot — Anthropic's crawler, used for both training and retrieval depending on context.
• PerplexityBot — Perplexity's crawler, tightly linked to its answer-with-sources product.
• Googlebot and Google-Extended — Googlebot is your classic search crawler; Google-Extended is the separate control for Gemini and AI training. Do not block Googlebot by accident while trying to block AI.

The distinction between the training bot and the retrieval bot is not academic. Data from Search Engine Journal, reporting on an Alli AI sample of 69 websites, found OpenAI's ChatGPT-User crawler made 3.6 times more requests than Googlebot between January and March 2026. The retrieval bot, not the training one, is doing the heavy lifting on live traffic.

How do you check which AI crawlers can access your site this week?

Here is a method you can run in about twenty minutes. Do not skip straight to a third-party checker and stop there — checkers read your robots.txt, but robots.txt is only part of the picture.

1. Read your own robots.txt. Go to yourdomain.com/robots.txt in a browser. Look for any User-agent: line naming GPTBot, ClaudeBot, PerplexityBot, ChatGPT-User or Google-Extended, and note whether it is followed by Disallow: /.
2. Run a free crawler checker. Tools like CrawlerCheck or the mrs.digital AI Crawler Access Checker take a domain and report which named bots your robots.txt allows or blocks. Use one to confirm what you read manually.
3. Pull your server logs — this is the step people skip. robots.txt is a request, not a wall. Filter your access logs (or your CDN's traffic analytics) by user-agent to see which AI bots are actually hitting you and how often. This is the only source of truth for real behavior.
4. Check the layers in front of your site. Your CDN or WAF — Cloudflare, for instance — may be blocking or challenging bots before your server ever sees them, regardless of what robots.txt says. Look at those rules directly.
5. Confirm search crawlers still get through. Before you touch anything, verify Googlebot and Bingbot can reach your public pages. Blocking them by mistake is the expensive error.

The mismatch between steps 1 and 3 is where the surprises live. We regularly find sites whose robots.txt politely asks bots to stay out while the logs show those same bots crawling freely — because robots.txt is voluntary and some crawlers ignore it.

How to use robots.txt to manage AI bots

robots.txt is the simplest control and the one you should set first. It is a plain text file at the root of your domain. To ask a specific AI crawler to stay out, you add its user-agent and a disallow rule:

• User-agent: GPTBot
Disallow: /
• User-agent: ClaudeBot
Disallow: /

To allow a bot, you simply leave it out — no rule means no restriction. You can also block training while allowing retrieval: disallow GPTBot but say nothing about ChatGPT-User, and you keep your citation potential while opting out of model training.

Managing bots this way is now mainstream. Analysis by Paul Calvano found AI crawlers like ChatGPT, Claude and Facebook named in the robots.txt files of more than 560,000 sites by 2025. One important caveat: robots.txt is a published instruction that well-behaved crawlers honor. It is not a firewall. If you need enforcement, that belongs at the CDN or server level — which is what step 4 above checks.

Should you block or allow AI Crawler Access?

This is where the honest answer is "it depends," and where most advice online quietly picks a side. Here is the case on each side, with the numbers we can stand behind.

The case for allowing. If you want your brand cited in AI answers, the retrieval bots have to be able to read you. Beyond access, structure matters: work citing Princeton's Generative Engine Optimization research found pages with authoritative citations appeared in 40% more generative responses, and pages carrying specific statistics saw a 37% lift in AI citation rates. Blocking the bots that fetch those pages forecloses that upside entirely.

The case for blocking. Some publishers do not want their content training models they do not control, and blocking is a clear way to set that boundary — useful if content licensing or a legal position matters to you. The comforting part: blocking rarely costs you human traffic. Raptive's analysis found sites that blocked one or more AI bots saw no statistically significant traffic change versus sites that did not, with average variation inside 1% as of the May–June 2025 window.

What we tell clients: allow retrieval bots if AI visibility is a goal, and treat the training question as a separate, deliberate decision tied to how you feel about your content being used. Do not block everything reflexively because a headline scared you.

Making an intentional AI Crawler Access policy

The point of all this is that AI Crawler Access should be a decision you made, not an accident you discover later. A workable policy has four parts.

1. Write it down. Document which bots you allow, which you block, and why. A one-page note beats a robots.txt file nobody can explain in six months.
2. Match it to a goal. If GEO and AI citations are on your marketing plan, your policy should let retrieval crawlers in. If licensing is your concern, block training crawlers specifically.
3. Monitor for drift. AI crawler volume is not static. Cloudflare's data shows crawler traffic rose 18% from May 2024 to May 2025, with GPTBot growing 305% in that span. A policy set once and never reviewed goes stale fast.
4. Re-check after any site change. A new CDN rule, a security plugin update or a migration can silently change who reaches your pages. Re-run the twenty-minute check.

Grid13 specializes in blog post creation using AI to improve SEO and GEO scores, and this policy question sits right at the front of that work — there is no point publishing content optimized for AI answers if the crawlers that generate those answers cannot read it. If you want that side handled alongside the content itself, that is exactly what the Grid13 platform is built to do.

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