What is Web Crawler?
An automated program that systematically browses the web to discover and index content.
A web crawler (also called a spider, bot, or web robot) is software that automatically traverses the web by following links from page to page. Crawlers download page content, extract links, and then visit those linked pages — repeating the process across millions or billions of URLs.
Search engines like Google use crawlers (Googlebot) to build their search index. AI companies use crawlers (GPTBot, ClaudeBot) to collect training data. SEO tools use crawlers (AhrefsBot, SemrushBot) to build backlink databases. Each crawler type has different goals, behaviors, and impact on your site.
Modern web crawlers range from simple scripts that follow links to sophisticated systems that render JavaScript, handle authentication, and simulate browser behavior. The line between "crawler" and "browser agent" is blurring as AI companies deploy agents that use real browsers to interact with websites.
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Switch detects and classifies 45+ different web crawlers in real-time, letting you build custom response workflows for each one.
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Googlebot
Google's primary web crawler powering the world's largest search engine.
GPTBot
OpenAI
OpenAI's training data crawler for GPT models including ChatGPT and GPT-4.
ClaudeBot
Anthropic
Anthropic's web crawler collecting training data for Claude models.
AhrefsBot
Ahrefs
Ahrefs' SEO crawler building the world's largest backlink database.