AI web crawlers are automated programs operated by AI companies that browse the internet to collect web content for training AI models, building search indexes, and powering real-time AI search features. As of 2026, at least eight major AI crawlers actively crawl the web, each operated by a different company and serving different purposes. Understanding which crawlers exist, what they do, and how to control access is essential for any startup focused on AI search optimization because crawler access is the first requirement for AI visibility - if a crawler cannot reach your content, the AI platform it serves cannot cite you.
According to Cloudflare's 2025 analysis, AI crawlers now account for 4.2% of all HTML requests across Cloudflare's network, with 80% of that crawling dedicated to model training, 18% to search, and 2% to user-initiated actions. Over 35% of the top 1,000 websites block at least one AI crawler, according to Originality.ai. For startups, this creates an opportunity - allowing full crawler access while larger competitors debate data rights gives you a visibility advantage in AI search results.
Which AI Crawlers Exist and What Do They Do?
| Crawler | Operator | User-Agent | Primary Purpose | AI Platform |
|---|---|---|---|---|
| GPTBot | OpenAI | GPTBot |
Model training data | ChatGPT |
| OAI-SearchBot | OpenAI | OAI-SearchBot |
Real-time web search | ChatGPT Search |
| ClaudeBot | Anthropic | ClaudeBot |
Model training data | Claude |
| Claude-SearchBot | Anthropic | Claude-SearchBot |
Search indexing | Claude Search |
| Claude-User | Anthropic | Claude-User |
User-requested page fetching | Claude |
| Google-Extended | Google-Extended |
AI model training | Gemini | |
| Applebot-Extended | Apple | Applebot-Extended |
AI feature training | Apple Intelligence |
| Bytespider | ByteDance | Bytespider |
Model training data | Doubao / TikTok AI |
| CCBot | Common Crawl | CCBot |
Open web archive | Used by many AI labs |
| Meta-ExternalAgent | Meta | Meta-ExternalAgent |
AI model training | Meta AI / Llama |
OpenAI Crawlers: GPTBot and OAI-SearchBot
OpenAI operates two crawlers with distinct roles. GPTBot crawls web content for model improvement and training. Content accessed by GPTBot may influence what ChatGPT "knows" in future model versions. OAI-SearchBot fetches pages in real time when a ChatGPT user triggers a web search query.
The distinction matters: blocking GPTBot prevents your content from entering training data but does not affect real-time search results. Blocking OAI-SearchBot prevents your content from appearing when ChatGPT users search the web. For maximum ChatGPT visibility, allow both.
OpenAI publishes its crawler documentation with IP ranges for verification.
Anthropic Crawlers: ClaudeBot, Claude-SearchBot, and Claude-User
Anthropic operates three crawlers. ClaudeBot collects content for model training. Claude-SearchBot indexes content for Claude's web search feature. Claude-User fetches specific pages when a user shares a URL with Claude.
Anthropic's three-bot architecture gives website owners granular control. You can allow search indexing and user-requested fetching while blocking training data collection - or allow everything for maximum visibility.
Anthropic documents its crawlers with instructions for robots.txt control.
Google-Extended
Google-Extended is Google's AI-specific crawler, separate from Googlebot which handles traditional search indexing. Google-Extended crawls content for training Gemini and other Google AI products. Blocking Google-Extended does not affect your Google Search rankings - it only prevents your content from being used for AI model training.
This separation is important. You can maintain full Google Search visibility while opting out of Gemini training data if desired. However, blocking Google-Extended may reduce your chances of being cited in Gemini's AI responses.
Applebot-Extended
Applebot-Extended is Apple's AI training crawler, introduced alongside Apple Intelligence features. It is separate from standard Applebot which handles Siri and Safari suggestions. Content crawled by Applebot-Extended may be used to train Apple's AI models for features like summarization, writing assistance, and Smart Reply.
As Apple Intelligence becomes more integrated into iOS, macOS, and Safari, content accessible to Applebot-Extended may gain visibility across Apple's ecosystem.
Bytespider
Bytespider is ByteDance's web crawler used for training AI models that power features across ByteDance's products, including TikTok's AI features and Doubao (ByteDance's ChatGPT competitor in China). Bytespider is one of the most aggressive AI crawlers by volume, making more requests per day than most other AI crawlers.
For startups focused primarily on Western AI search platforms, Bytespider's impact on visibility is less direct than GPTBot or ClaudeBot. However, blocking it is unnecessary unless you have specific concerns about ByteDance's data practices.
CCBot (Common Crawl)
CCBot crawls the web for the Common Crawl project, an open repository of web data used by many AI companies and researchers as training data. Unlike company-specific crawlers, CCBot feeds an open dataset that multiple AI labs access. Blocking CCBot can reduce your presence across multiple AI platforms simultaneously.
Meta-ExternalAgent
Meta-ExternalAgent is Meta's crawler for AI model training, used to build training datasets for Meta AI and the Llama family of open-source models. As Meta AI is integrated into Facebook, Instagram, and WhatsApp, content crawled by Meta-ExternalAgent could influence responses across Meta's social platforms.
How Do You Control AI Crawler Access?
All major AI crawlers respect robots.txt directives. To allow all AI crawlers:
User-agent: GPTBot
Allow: /
User-agent: OAI-SearchBot
Allow: /
User-agent: ClaudeBot
Allow: /
User-agent: Claude-SearchBot
Allow: /
User-agent: Claude-User
Allow: /
User-agent: Google-Extended
Allow: /
User-agent: Applebot-Extended
Allow: /
User-agent: Bytespider
Allow: /
User-agent: CCBot
Allow: /
User-agent: Meta-ExternalAgent
Allow: /
To allow search-focused crawlers but block training data crawlers:
User-agent: OAI-SearchBot
Allow: /
User-agent: Claude-SearchBot
Allow: /
User-agent: Claude-User
Allow: /
User-agent: GPTBot
Disallow: /
User-agent: ClaudeBot
Disallow: /
User-agent: Google-Extended
Disallow: /
Which Crawlers Should Startups Prioritize?
For startups focused on AI search visibility, the priority order is:
- GPTBot + OAI-SearchBot - ChatGPT has the largest AI search user base
- ClaudeBot + Claude-SearchBot - Claude is growing rapidly and is heavily used by technical and professional audiences
- Google-Extended - Gemini is integrated into Google Search, reaching billions of users
- All others - Allow them for comprehensive coverage unless you have specific data concerns
The practical recommendation for most startups: allow all crawlers. The visibility benefits far outweigh the data usage concerns, and blocking any crawler reduces your potential AI search visibility.
For a step-by-step guide to reviewing your current crawler settings, see our guide on how to audit AI crawler access.