AI Crawlers explained: How bots are reading your site

Your website traffic logs are lying to you.

They show Googlebot indexing your pages. They show users from Chrome and Safari. But they might be missing the most aggressive new visitors on the web: AI Crawlers.

Unlike traditional search engine bots, which scan your site to rank it, AI crawlers scan your site to learn it. They are harvesting your content to train the next generation of Large Language Models (LLMs).

The decision you make today, to block them or welcome them, will shape your visibility in the AI era.

Table of contents

• Search bots vs AI crawlers
• The big list of AI user agents
• To block or not to block?
• How to control them
• Monitoring the invisible traffic

Search bots vs AI crawlers

For 20 years the deal was simple: you give Google your content, Google gives you traffic.

AI crawlers break that contract.

Feature	Googlebot	GPTBot / ClaudeBot
Goal	Index links for search	Ingest text for training
Output	Blue link to your site	Synthesized answer
Traffic	Direct click-throughs	Often zero clicks
Value	SEO & Visibility	GEO & Brand Authority

The friction. If an AI reads your article and learns everything in it, it can answer user questions without ever sending that user to your site. This is the “Zero-Click” future that AEO prepares us for.

The big list of AI user agents

There isn’t just one bot anymore. Here are the key agents to know in 2026.

1. GPTBot (OpenAI)

The big one. It crawls the web to train GPT-4 and GPT-5 models.

• User agent. GPTBot
• Impact. High. Blocking it removes your data from future model training.

2. ClaudeBot (Anthropic)

Aggressive and thorough. Used to train the Claude family of models.

• User agent. ClaudeBot
• Impact. High. Claude has large context windows, so it digests entire long-form articles in one pass.

3. Google-Extended

Google’s compromise. This token lets you block your content from training Gemini without de-indexing from Google Search.

• User agent. Google-Extended
• Note. This does not affect your SEO rankings.

4. PerplexityBot

Powering the “Answer Engine.” Unlike training bots, this one often fetches data live to answer user queries.

• User agent. PerplexityBot
• Impact. Immediate visibility in Perplexity search results.

To block or not to block?

This is a business decision as much as a technical one.

Block them if:

• Your content is your product (e.g., New York Times, paywalled research).
• You have sensitive IP and don’t want your proprietary code or data ending up in a public model.
• Server costs are high. AI bots can be aggressive and expensive to serve.

Allow them if:

• You want brand visibility, so ChatGPT knows who you are and recommends you.
• You are in B2B, where being cited as an authority in an AI answer is valuable social proof.
• You practice AI SEO and actively optimize content to be consumed by machines.

How to control them

You control these bots through your robots.txt file.

To block all major AI training bots:

User-agent: GPTBot
Disallow: /

User-agent: ClaudeBot
Disallow: /

User-agent: Google-Extended
Disallow: /

User-agent: CCBot
Disallow: /

To allow them but keep them out of admin areas:

User-agent: GPTBot
Allow: /
Disallow: /admin/
Disallow: /private/

Note: implementing llms.txt is a proactive way to guide these bots to the right content, instead of just blocking them via robots.txt.

Monitoring the invisible traffic

Standard analytics tools like GA4 filter out “bot traffic” by default. You might be getting thousands of AI visits a day and never know it.

Why it matters. If GPTBot stops visiting your site, your fresh content isn’t making it into the model and you go stale to the AI.

The fix is specialized monitoring.

cloro helps you close the loop. Server logs tell you if the bot visited; cloro tells you if the model actually remembers you.

By tracking your brand mentions across LLMs, you can correlate robots.txt changes with your actual AI visibility.

Control who reads your site, and verify what they learn.