What are AI crawlers?
AI bots, LLM crawlers, GPTBot, PerplexityBot
AI crawlers are bots that AI companies use to fetch web pages. Some collect training data, some build search indexes, and some retrieve a page live when a user asks a question. Common examples include GPTBot, OAI-SearchBot, ChatGPT-User, ClaudeBot and PerplexityBot. If they cannot reach your pages, AI engines cannot cite them.
AI crawlers fetch pages for training, search indexing or live answers.
Blocking the wrong bot can remove your site from AI search answers.
Many AI crawlers do not run JavaScript, so key content belongs in HTML.
Types of AI crawlers
AI crawlers fall into three main types, and each affects your visibility differently.
Training crawlers collect pages to train future models. GPTBot (OpenAI) and ClaudeBot (Anthropic) are examples. Blocking them affects what future models learn, not live search results.
Search crawlers build the index an AI engine searches when it answers. OAI-SearchBot supports ChatGPT search, and PerplexityBot builds the Perplexity index.
User-triggered fetchers load a specific page in real time because a user asked about it or the engine wants to read it. ChatGPT-User and Perplexity-User are examples.
Google works differently. Google-Extended is not a separate crawler but a robots.txt control that tells Google whether content may be used for Gemini models. Google AI Overviews rely on the regular Googlebot index, as covered in robots.txt for AI.
How AI crawlers differ from Googlebot
AI crawlers differ from Googlebot mainly in how they render pages. Googlebot renders JavaScript and returns to pages on a regular schedule. Many AI crawlers fetch only the raw HTML and do not execute JavaScript, so content loaded in the browser after the page loads may be invisible to them.
That makes server-side rendering important. If your product details, prices or reviews only appear after scripts run, an AI crawler may see an almost empty page.
AI crawlers also follow robots.txt rules written for each bot, so a site can allow Googlebot while blocking an AI bot by accident. Some content delivery networks and security tools can block AI bots by default, which can cut a site out of AI answers without anyone on the marketing team noticing.
How to control AI crawler access
AI crawler access is controlled mainly through robots.txt, with each bot addressed by its user agent name. A site that wants to appear in AI search but stay out of model training might use rules like these:
User-agent: OAI-SearchBotfollowed byAllow: /to stay in ChatGPT search resultsUser-agent: GPTBotfollowed byDisallow: /to opt out of OpenAI model trainingUser-agent: PerplexityBotfollowed byAllow: /to stay in the Perplexity index
Rules in robots.txt are requests that reputable bots follow, not technical barriers. Also check firewall, CDN and bot-protection settings, since these can block AI crawlers even when robots.txt allows them. An llms.txt file does not change access at all. Confirm in your server logs that the bots you allow actually get through.
Why AI crawlers matter for your brand
AI crawlers matter because they are how your pages enter AI answers. If OAI-SearchBot cannot reach your pricing page, ChatGPT search cannot cite it, and the engine will rely on third-party pages to describe your prices instead.
Crawler access is also one of the easiest visibility problems to fix. Content quality takes time to improve, but a blocked bot or a page that renders empty can often be fixed in a day. That is why AI website health checks usually start with crawlability.
Crawler activity in server logs is also an early signal. Frequent visits from user-triggered fetchers show that AI engines are reading your pages in response to real questions, even before any AI referral traffic shows up in your analytics.
How KIME checks AI crawler access
KIME AI Web Health checks whether AI engines can access and read your site. It flags technical issues that stop pages from being retrieved, such as blocked AI bots or content that only appears after JavaScript runs, and turns them into technical tasks in Actions. AWX agents can help carry out technical fixes, so crawlability problems do not sit in a backlog while competitors get cited instead.
Frequently asked questions
Should I block GPTBot?
Blocking GPTBot stops OpenAI from using your pages to train future models, but it does not remove you from ChatGPT search, which uses OAI-SearchBot and ChatGPT-User. Many brands allow all three because training data can also shape how models describe them. Publishers whose content is the product often weigh this choice differently.
How can I tell if AI crawlers visit my site?
Check your server or CDN logs for AI crawler user agents such as GPTBot, OAI-SearchBot, ChatGPT-User, ClaudeBot and PerplexityBot. Logs show which pages they request and whether they get a successful response. Standard analytics tools usually miss bot visits because most crawlers do not run the JavaScript tracking code those tools rely on.
Do AI crawlers follow robots.txt?
The major AI companies say their crawlers respect robots.txt, and you can address each bot by its user agent name. Robots.txt is a voluntary standard, though, so it relies on the crawler choosing to obey it. Some user-triggered fetchers are treated differently because they act on a specific user request, so check each company's documentation.