AI crawlers are automated bots that scan websites to collect data for training large language models like ChatGPT, Claude, and Gemini. Unlike traditional search engine crawlers that index content for retrieval, AI crawlers extract information to improve AI systems’ knowledge and capabilities. Understanding these crawlers helps website owners control how their content is used in AI training.
The internet is undergoing a fundamental shift. For decades, traditional search engine crawlers like Googlebot methodically indexed websites to help people find information. Now, a new generation of AI-powered crawlers is scanning the web with a different purpose: feeding the massive data requirements of artificial intelligence systems.
If you manage a website, you’re likely already hosting visits from ChatGPT’s crawler, Claude’s bot, and dozens of other AI systems you’ve never heard of. These bots are different from the ones you’re used to. They read your content differently, respect different rules, and serve a fundamentally different purpose.
This guide breaks down everything you need to know about AI crawlers: what they are, how they differ from traditional crawlers, which major players you should know, and how to control their access to your website.
Understanding Web Crawlers: Traditional vs AI
Before diving into AI crawlers specifically, it’s helpful to understand the foundation they’re built upon.
How Traditional Web Crawlers Work
Traditional web crawlers are automated programs that systematically browse the internet to index content for search engines. Think of them as digital librarians who catalog information based on HTML structures, metadata, and keywords.
The process follows three main stages:
Discovery and Crawling: Crawlers start with a list of web addresses from past crawls and sitemaps provided by website owners. As they visit pages, they identify links to discover new content.
Information Extraction: While visiting web pages, crawlers extract useful information including page content, metadata like titles and descriptions, and the HTML structure that organizes everything.
Storage and Indexing: The extracted information gets processed and stored in organized search indexes that can be quickly queried when users perform searches.
Traditional crawlers like Googlebot, Bingbot, and YandexBot excel at handling static websites with well-organized content. But they struggle with dynamic websites featuring complex JavaScript applications, frequently changing structures, and context-dependent information.
What Makes AI Crawlers Different
AI crawlers represent a quantum leap in web indexing technology. Unlike their predecessors, these systems use advanced machine learning algorithms and natural language processing to understand content contextually, much like a human reader would.
Here’s what distinguishes AI crawlers:
Context Awareness: AI crawlers don’t just read text, they understand meaning, tone, and purpose. They can interpret whether a page is instructional, promotional, or informational.
Flexibility: These crawlers identify and adapt to website changes in real-time without manual updating. If your site structure changes, they figure it out.
Semantic Understanding: AI crawlers interpret natural language and relationships between different pieces of content. They understand that “Big Apple” means New York City in context.
Real-Time Adaptation: They learn and adjust based on discovered content without human interaction. Each crawl makes them smarter about your site.
The fundamental difference lies in purpose. Traditional crawlers index content so people can find it through search. AI crawlers download content specifically to train large language models. This creates an entirely new category of web traffic with different behaviors, priorities, and implications for website owners.
Major AI Crawlers You Need to Know in 2025
The AI crawler landscape is crowded and constantly evolving. Here are the major players you’ll encounter.
OpenAI Crawlers
OpenAI operates three distinct crawlers, each serving different functions within their ecosystem.
| Crawler Name | Purpose | User Agent |
|---|---|---|
| GPTBot | Primary offline crawler that collects publicly available data to train and improve AI models like GPT-4 | Mozilla/5.0 AppleWebKit/537.36 (KHTML, like Gecko); compatible; GPTBot/1.1 |
| ChatGPT-User | Indicates a real user query prompted ChatGPT to crawl your website in real-time to fetch current content | ChatGPT-User (identifies real-time user requests) |
| OAI-SearchBot | Indexing bot that runs asynchronously to augment search results from Bing and other sources | OAI-SearchBot (for search functionalities) |
GPTBot crawls asynchronously, meaning your website may be used to train AI models even if it doesn’t rank in GPT search results. ChatGPT-User provides the best signal of visibility in ChatGPT results, making it crucial for boosting presence in AI-generated answers. OpenAI’s crawlers respect robots.txt directives and operate from specific IP address blocks you can find in JSON files hosted at openai.com.
Anthropic’s Claude Crawlers
Anthropic uses multiple bots to support its Claude AI assistant, each with specific roles.
| Crawler Name | Purpose | User Agent |
|---|---|---|
| ClaudeBot | Main crawler for model training that visits public websites to collect data for improving Claude’s long-term knowledge | Mozilla/5.0 AppleWebKit/537.36 (KHTML, like Gecko); compatible; ClaudeBot/1.0 |
| Claude-User | Appears when a user query prompts Claude to retrieve real-time information, fetching content on-demand | Claude-User (real-time retrieval) |
| Claude-SearchBot | Evaluates web pages for Claude’s internal search feature to increase visibility in embedded search results | Claude-SearchBot (search indexing) |
All of Claude’s bots respect the Robots Exclusion Protocol, observe crawl delay rules, and don’t circumvent access restrictions like CAPTCHAs or authentication walls. If you block Claude-User, Claude can’t include your pages in live, cited answers.
Google’s AI Crawlers
Google operates two distinct AI crawlers separate from traditional Googlebot.
Google-Extended was introduced in September 2023 to give website owners granular control over how their content is used for AI training. It specifically collects data for training Google’s Gemini (formerly Bard) and Vertex AI generative APIs, separate from traditional Google Search indexing.
The user agent string is: Mozilla/5.0 AppleWebKit/537.36 (KHTML, like Gecko; compatible; Google-Extended/1.0
Website owners can block Google-Extended through robots.txt without affecting their Google Search visibility. This provides clear separation between search indexing and AI training data collection.
Google-Gemini has a significant technical advantage over other LLM crawlers. It inherits Googlebot’s full JavaScript rendering capabilities. This means Gemini can crawl and index client-side rendered content, including React or Vue applications, dynamic SPAs, and content fetched asynchronously. Recent analysis shows none of the other major AI crawlers (OpenAI, Claude, Perplexity) currently execute JavaScript.
Perplexity Crawlers
Perplexity operates two distinct crawlers, though their behavior has sparked controversy.
| Crawler Name | Purpose | Respects Robots.txt |
|---|---|---|
| PerplexityBot | Designed to surface and link websites in search results on Perplexity’s platform (not for AI training) | Yes (in theory) |
| Perplexity-User | Supports user actions, visiting web pages to provide accurate answers when users ask questions | No (user-initiated) |
The user agent for PerplexityBot is: Mozilla/5.0 AppleWebKit/537.36 (KHTML, like Gecko; compatible; PerplexityBot/1.0
PerplexityBot has faced anecdotal reports of ignoring robots.txt directives, though the company claims compliance. These reports raise concerns among webmasters about data security and resource consumption.
Other Major AI Crawlers
Several other companies operate significant AI crawlers you should know about.
Meta-ExternalAgent: Quietly launched in July 2024, this crawler scrapes web content for training AI models and improving Meta’s products. The user agent string is: meta-externalagent/1.1. Meta hasn’t publicly announced this crawler beyond updating a corporate website for developers.
Bytespider: Launched in April 2024 by ByteDance (TikTok’s parent company), this has become one of the most aggressive scrapers on the internet. Some third-party monitoring reports suggest Bytespider scrapes far more aggressively than GPTBot or ClaudeBot, though exact multipliers vary and are unverified. Data shows huge spikes in scraping activity, with anecdotal reports suggesting it may not consistently respect robots.txt directives.
Amazonbot: Amazon’s web crawler used to improve services, particularly enabling Alexa to more accurately answer questions. It respects the robots.txt protocol and honors allow/disallow directives. The user agent is: Amazonbot/0.1.
CCBot: Operated by Common Crawl, a non-profit organization that builds and maintains an open repository of web crawl data accessible to anyone. This extensive dataset is used by researchers, businesses, and AI companies to train large language models. OpenAI, Google T5, Meta, Hugging Face, and other major AI companies use Common Crawl data to train their models. CCBot has been active since around 2011 and crawls approximately once a month.
Apple Crawlers: Apple operates Applebot for Siri and Spotlight search, plus Applebot-Extended (introduced June 2024) which evaluates content already indexed to determine suitability for training Apple’s AI models. Applebot-Extended doesn’t crawl webpages directly but determines how data collected by the primary Applebot will be used.
Bingbot: Microsoft’s standard crawler handles most crawling needs for the Bing search engine and now supports AI features. Bingbot uses the most stable version of Microsoft Edge for webpage rendering. The user agent follows this format: Mozilla/5.0 AppleWebKit/537.36 (KHTML, like Gecko; compatible; bingbot/2.0.
How to Control AI Crawler Access
You have several options for controlling which AI crawlers can access your website and how they behave.
Using Robots.txt
The robots.txt file is your primary tool for controlling crawler access. It’s a text file placed in your website’s root directory that tells crawlers which parts of your site they can access.
Here’s how to block specific AI crawlers:
# Block OpenAI's GPTBot
User-agent: GPTBot
Disallow: /
# Block Anthropic's ClaudeBot
User-agent: ClaudeBot
Disallow: /
# Block Google's AI training (not search)
User-agent: Google-Extended
Disallow: /
# Block Common Crawl
User-agent: CCBot
Disallow: /
# Block ByteDance's Bytespider
User-agent: Bytespider
Disallow: /
You can learn more about robots.txt implementation in the official Google Search Central documentation.
You can also allow crawlers but set rate limits:
User-agent: GPTBot
Crawl-delay: 10
Disallow: /private/
This tells GPTBot to wait 10 seconds between requests and stay out of your private directory.
To block all AI crawlers while allowing traditional search engines:
# Allow Googlebot
User-agent: Googlebot
Allow: /
# Block all AI crawlers
User-agent: GPTBot
User-agent: ClaudeBot
User-agent: CCBot
User-agent: Google-Extended
User-agent: Bytespider
User-agent: PerplexityBot
User-agent: Amazonbot
User-agent: meta-externalagent
Disallow: /
Blocking Strategies
Deciding whether to allow or block AI crawlers depends on your specific situation.
When to Allow AI Crawlers:
You run a news site or blog where visibility in AI answers drives traffic. Your business benefits from being cited as a source in AI responses. You want to participate in AI training to influence how models understand your industry. You’re comfortable with your content being used for AI development.
When to Block AI Crawlers:
You have proprietary content or trade secrets you want to protect. Your server resources are limited and can’t handle aggressive crawling. You’re concerned about content being used without compensation. You want to maintain control over how your intellectual property is used. You’ve experienced performance issues from bot traffic.
IP-Based Blocking: Some crawlers ignore robots.txt directives. For these, you’ll need to block their IP addresses at the server level using .htaccess files or your web application firewall.
Rate Limiting: Even if you allow crawlers, you can limit how frequently they access your site to prevent server overload. Most well-behaved crawlers respect crawl-delay directives in robots.txt.
Best Practices for Website Owners
Managing AI crawlers effectively requires more than just blocking decisions.
Crawl Budget Optimization
Your crawl budget is the number of pages search engines and AI crawlers will visit on your site in a given timeframe. Don’t waste it on low-value pages.
Use robots.txt to block crawlers from admin pages, search result pages, duplicate content, and temporary pages. Update your XML sitemap regularly to guide crawlers to your most important content. Monitor your server logs to identify wasteful crawling patterns. Consider technical SEO optimization to ensure your site is configured properly for crawler efficiency.
Sitemap Management
A well-maintained XML sitemap helps both traditional and AI crawlers understand your site structure. Include all important pages with accurate last-modified dates. Submit your sitemap to Google Search Console. Update it whenever you publish new content or make significant changes.
Server-Side Rendering for JavaScript Sites
Since most AI crawlers can’t execute JavaScript (except Google-Gemini), sites built with React, Vue, or Angular need server-side rendering to ensure their content is accessible. Implement SSR or use pre-rendering services. Test your pages with crawlers that don’t execute JavaScript. Provide fallback content for dynamic elements.
Schema Markup Importance
Structured data helps AI crawlers understand your content’s context and relationships. Implement Article schema for blog posts and news. Use FAQ schema for question-answer content. Add Organization schema for business information. Include Product schema for e-commerce sites. Professional schema markup implementation ensures AI systems can properly interpret and reference your content.
Monitoring Crawler Activity
Regular monitoring helps you spot problems early. Check your server logs weekly for unusual bot activity. Use Google Search Console to monitor crawl stats. Set up alerts for sudden increases in bot traffic. Track which crawlers are accessing which pages.
The Impact of AI Crawlers on Your Website
AI crawlers affect your website in several ways beyond just the philosophical questions about content usage.
Performance Considerations
Aggressive AI crawlers can slow down your website for real users. Bytespider, for example, has been reported as one of the most aggressive crawlers based on third-party monitoring data. This can overwhelm servers not equipped to handle the load.
Monitor your server resources during peak crawling times. Implement rate limiting for aggressive bots. Consider upgrading hosting if bot traffic regularly impacts performance. Use a content delivery network (CDN) to distribute the load.
Bandwidth Usage
AI crawlers consume bandwidth, which can increase hosting costs if you’re on a metered plan. Large sites with extensive content may see significant bandwidth usage from multiple AI crawlers visiting regularly.
Track bandwidth usage by user agent. Block the most aggressive crawlers if costs become an issue. Consider compressed content delivery to reduce bandwidth per request.
Legal and Ethical Considerations
The legal landscape around AI web scraping remains unsettled. Some questions to consider: Do AI crawlers have the right to use your content without permission? Should you be compensated if your content trains commercial AI systems? Can you enforce licensing terms through robots.txt alone?
Currently, robots.txt provides a way to indicate your preferences, but it’s not legally binding. Some crawlers ignore it entirely. Future regulations may provide clearer guidance on AI training data usage.
Future Implications
The AI crawler ecosystem is evolving rapidly. More AI companies will launch their own crawlers. Existing crawlers will become more sophisticated and resource-intensive. New standards may emerge for controlling AI access. Websites may gain more tools for monetizing AI training data.
Staying informed about these changes helps you make better decisions about managing crawler access to your content.
Frequently Asked Questions
What’s the difference between traditional crawlers and AI crawlers?
Will blocking AI crawlers hurt my search engine rankings?
How do I know which AI crawlers are visiting my website?
Do all AI crawlers respect robots.txt directives?
Should I allow or block AI crawlers on my business website?
Can AI crawlers access content behind login pages or paywalls?
How often do AI crawlers visit websites?
What happens if I block an AI crawler after it’s already crawled my site?
Key Takeaways
- AI crawlers serve a different purpose than traditional search crawlers. They collect content to train large language models rather than indexing for search results. Understanding this distinction helps you make informed decisions about crawler access.
- Major AI companies operate multiple specialized crawlers. OpenAI has GPTBot, ChatGPT-User, and OAI-SearchBot. Anthropic uses ClaudeBot, Claude-User, and Claude-SearchBot. Each serves different functions within its AI ecosystem.
- You can control AI crawler access through robots.txt. Block specific crawlers, set rate limits, or restrict access to certain directories. Most reputable AI crawlers respect these directives, though some aggressive crawlers ignore them.
- Blocking AI crawlers won’t hurt your search rankings. AI training crawlers are separate from search engine crawlers like Googlebot. You can block Google-Extended while maintaining full Google Search visibility.
- Monitor crawler activity to protect server resources. Aggressive crawlers like Bytespider can overload your server. Regular log monitoring helps you identify and block problematic bots before they impact website performance.
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