Quick answer: AI crawlers identify themselves by user agent: GPTBot and OAI-SearchBot (OpenAI), ClaudeBot (Anthropic), PerplexityBot, Google-Extended (Google AI training), Bytespider (ByteDance), Amazonbot and others. Detect them in server access logs, hosting analytics or CDN dashboards by filtering user-agent strings – and verify authenticity via published IP ranges, since fakes are common.
The AI crawlers worth watching
Training crawlers: GPTBot, ClaudeBot, Google-Extended, Meta-ExternalAgent, Bytespider – feed model training. Retrieval crawlers: OAI-SearchBot, PerplexityBot, and on-demand fetchers like ChatGPT-User and Perplexity-User – fetch pages when engines answer live queries. Retrieval visits matter most commercially: they mean an engine considered citing you in a real answer.
Three ways to detect them
1. Server access logs. Filter raw logs for the user-agent strings above (hosting panels expose these; a quick grep works everywhere). Log lines show which pages each bot fetched, how often, and what status codes they received.
2. CDN and firewall dashboards. Cloudflare and similar services classify AI crawlers explicitly and chart their traffic – the fastest view, and where you would discover accidental blocking.
3. Analytics segments for AI referrals. Not crawlers, but their consequence: human visitors arriving from chatgpt.com, perplexity.ai and gemini.google.com prove citations exist (GA4 setup guide).
Reading the patterns
No AI bot visits at all? Check robots.txt and firewall rules – you may be blocking them (what to allow). Bots hitting only your homepage? Internal linking or sitemap problems. Lots of 403/429 responses? Your security layer is challenging bots you meant to allow. Retrieval bots hitting specific guides repeatedly? Those pages are being cited – protect and update them.
Verify before you trust
Scrapers impersonate reputable bots to bypass rules. OpenAI, Anthropic, Google and Perplexity publish official IP ranges – verify suspicious traffic against them before whitelisting, and never grant special access on user-agent alone.
FAQ
How often should AI crawlers visit?
Active sites see GPTBot and PerplexityBot weekly or better. Absence for a month signals an access problem worth auditing – IndexGraph.ai‘s crawler audit checks every major bot’s access in minutes.
Not sure whether AI engines can even reach your site? Adexorb Technologies starts every GEO program with a full crawler access audit.