AI assistants like ChatGPT, Claude, and Perplexity don't just use their training data — they also crawl the live web to fetch current information. The bots doing that crawling are called AI crawlers, and they're visiting millions of websites every day. This guide covers every major AI crawler, what they do, and how to manage them.
What Are AI Crawlers?
AI crawlers are automated programs (bots) that browse the web on behalf of AI companies. They serve two main purposes:
- Training data collection: Crawling the web to gather text data used to train large language models (LLMs). This typically happens periodically, before a new model is trained.
- Real-time retrieval: Fetching current web content to answer user questions with up-to-date information. This happens every time a user asks a question that requires live data.
Unlike Googlebot (which helps your site rank in search), AI crawlers determine whether your content gets included in AI-generated answers. Blocking them means AI assistants can't reference your site. Allowing them means AI can learn from and cite your content.
Major AI Crawlers in 2026
GPTBot (OpenAI)
The crawler used by OpenAI to collect training data for GPT models and to power ChatGPT's web search feature. If you block GPTBot, your content won't appear in ChatGPT responses. OpenAI publishes its IP ranges and respects robots.txt.
ClaudeBot (Anthropic)
Anthropic's web crawler used to collect training data and power Claude's web access features. Respects robots.txt directives. Blocking ClaudeBot prevents your content from appearing in Claude's responses.
PerplexityBot
Perplexity is an AI-native search engine that crawls the web in real time to generate cited answers. PerplexityBot fetches pages constantly to keep its index fresh. Blocking it removes your site from Perplexity's results.
GoogleBot (AI Overviews)
Googlebot powers both traditional Google Search and Google's AI Overviews (formerly SGE). The same crawler serves both purposes — blocking Googlebot affects your traditional rankings and your AI Overview visibility simultaneously.
BingBot / Copilot
Microsoft's Bing crawler powers both Bing Search and Microsoft Copilot. Allowing bingbot gives your content visibility in Copilot's AI-generated answers as well as traditional Bing rankings.
CCBot (Common Crawl)
Common Crawl is a non-profit that archives the web and makes the data freely available. Many AI companies use Common Crawl datasets for training — so blocking CCBot may exclude your content from multiple models' training data.
AI Crawler Summary Table
| Crawler | Company | Purpose | Respects robots.txt? |
|---|---|---|---|
| GPTBot | OpenAI | Training + ChatGPT web search | Yes |
| ClaudeBot | Anthropic | Training + Claude web access | Yes |
| PerplexityBot | Perplexity AI | Real-time search index | Yes |
| Googlebot | Search + AI Overviews | Yes | |
| bingbot | Microsoft | Search + Copilot | Yes |
| CCBot | Common Crawl | Open web archive (used for training) | Yes |
How to Allow or Block AI Crawlers in robots.txt
robots.txt is a plain text file at yourdomain.com/robots.txt that tells crawlers which pages they can and cannot access. All major AI crawlers respect robots.txt.
Allow all AI crawlers (recommended for most sites)
User-agent: *
Allow: /
# Explicitly allow AI crawlers
User-agent: GPTBot
Allow: /
User-agent: ClaudeBot
Allow: /
User-agent: PerplexityBot
Allow: /Block specific AI crawlers
# Block OpenAI's training crawler only
User-agent: GPTBot
Disallow: /
# Block Anthropic's crawler
User-agent: ClaudeBot
Disallow: /Block all AI crawlers (not recommended)
User-agent: GPTBot
Disallow: /
User-agent: ClaudeBot
Disallow: /
User-agent: PerplexityBot
Disallow: /
User-agent: CCBot
Disallow: /Note: Blocking AI crawlers removes your site from AI-generated answers and recommendations. For most businesses, this is the opposite of what you want. Only block if you have specific legal or commercial reasons to do so.
How AI Crawlers Use Your llms.txt File
When an AI crawler visits your site, it typically fetches several files to understand your content:
robots.txt— to know what it can accessllms.txt— to get a structured summary of your site (if it exists)- Individual pages — to read your actual content
The llms.txt file is the key difference. Rather than forcing AI crawlers to infer what your site is about from raw HTML, llms.txt gives them a clean, structured Markdown brief. This includes:
- Your site name and one-paragraph description
- Your most important pages with descriptions
- Your products, services, or expertise areas
- Optional: links to full documentation, API references, or detailed guides
Sites with an llms.txt file give AI crawlers a reliable, curated source of truth — which tends to produce more accurate AI-generated descriptions and citations.
Should You Allow or Block AI Crawlers?
For most websites, the answer is allow them. AI-powered search is growing rapidly, and being cited by ChatGPT, Claude, or Perplexity drives real referral traffic. Blocking AI crawlers now means missing out on a growing discovery channel.
Consider blocking only if:
- Your content is behind a paywall and you don't want it used for training data
- You have legal reasons to restrict content reproduction
- You sell AI-generated content and want to protect it from being recycled
For paywalled content, you can allow crawling of your public pages while blocking the gated content — getting the discovery benefit without the content risk.
Make your site AI-crawler ready
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