Every major AI platform sends crawlers to fetch web content. These crawlers are what feed the AI systems that generate answers. Understanding how they work is the foundation of any GEO or AI visibility strategy.
The major AI crawlers
GPTBot (OpenAI / ChatGPT)
GPTBot is OpenAI's web crawler, identified by the user agent string GPTBot. It fetches pages to build and update the knowledge that ChatGPT uses when generating answers. GPTBot respects robots.txt directives and does not execute JavaScript. It processes the raw HTML response and extracts text content, heading structure, and any structured data present.
PerplexityBot (Perplexity AI)
PerplexityBot crawls pages in real time when users ask questions. Unlike GPTBot, which pre-crawls for training, Perplexity often fetches pages at query time to generate citation-backed answers. This means your page needs to be immediately parseable — there is no grace period. PerplexityBot looks for direct answers, quotable statements, and factual claims it can cite with a source link.
ClaudeBot (Anthropic / Claude)
Anthropic's crawler fetches content for Claude's knowledge base. ClaudeBot is identified by the ClaudeBot or anthropic-ai user agent. It processes HTML for content extraction with a focus on reasoning context — it benefits from content that explains not just what something is, but why it matters and how it compares to alternatives.
Google-Extended (Gemini)
Google uses the Google-Extended user agent to crawl content specifically for Gemini and other AI products (separate from Googlebot which crawls for Search). This crawler focuses on entity relationships, brand authority signals, and knowledge-graph-compatible structured data.
What AI crawlers have in common
- No JavaScript execution. They fetch HTML and parse it directly. Client-rendered content is invisible.
- No visual rendering. Layout, design, images, and interactive elements are ignored. Only text and structure matter.
- Robots.txt compliance. All major AI crawlers respect robots.txt, so you can control access.
- Structured data preference. JSON-LD, schema.org markup, and clean heading hierarchies make content significantly easier to extract.
What they process differently
Each AI system synthesizes content differently based on its architecture and purpose:
- ChatGPT benefits from comprehensive, schema-rich context — it uses broad information to construct detailed answers.
- Perplexity benefits from direct, quotable facts — it constructs citation-backed answers in real time.
- Claude benefits from reasoning context — explanations of trade-offs, comparisons, and contextual relationships.
- Gemini benefits from entity-aligned data — clear brand identity, product categories, and knowledge-graph-compatible structure.
What this means for your site
A single HTML response cannot be optimized for all four crawlers simultaneously — they look for different things. This is why adaptive rendering exists: serve each crawler a response profile tailored to how that specific AI system processes information, while keeping your human-facing site unchanged.