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Stop LLM Crawlers in 2025: How to Block AI Bots on Your Website

#whoerip #llm #robots #crawlers

AI crawlers are no longer a niche phenomenon — in 2025 they represent a huge share of global web traffic. From GPTBot (OpenAI) to ClaudeBot (Anthropic), PerplexityBot, Google-Extended, and Meta-ExternalAgent, these automated visitors hit websites every day.

While some crawlers help with visibility in AI search results, others consume bandwidth and scrape data for training models — often without your consent. For many site owners, this feels less like indexing and more like being mined for free data.

Why Block Them?

Prevent your site from being used to train third-party AI models

Reduce server load and bandwidth waste

Protect sensitive or premium content from automated scraping

Example User Agents to Watch For

Google-Extended (+https://developers.google.com/search/docs/crawling-indexing/overview-google-extended)

First Step: robots.txt

The easiest way to start blocking is with robots.txt. Add rules for each unwanted crawler:

User-agent: GPTBot
Disallow: /

User-agent: ClaudeBot
Disallow: /

User-agent: PerplexityBot
Disallow: /
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This will stop compliant bots immediately. But remember — not every crawler respects robots.txt. For persistent ones, you’ll need server-level blocking, rate limiting, or Fail2ban (see full guide here).

Should You Block All LLM Crawlers?

Blocking AI crawlers sounds like the obvious move — but the reality is more nuanced. Not every crawler is harmful, and some may actually help your website.

✅ Pros of Blocking

Content protection – prevents your articles, reports, or proprietary data from being reused in AI training without permission.

Server performance – reduces unnecessary requests, saving CPU, memory, and bandwidth.

Security and compliance – keeps sensitive or regulated information out of AI datasets.

Competitive edge – stops rivals’ AI tools from learning directly from your content.

❌ Cons of Blocking

Lost visibility in AI search – assistants like Perplexity or ChatGPT may stop recommending your site if their crawlers are blocked.

Reduced referral traffic – AI platforms often cite or link back to sources; blocking cuts off this channel.

SEO uncertainty – while blocking AI crawlers won’t hurt Google SEO directly, future search rankings may involve AI signals.

Missed opportunities – some AI-powered platforms can bring in highly qualified visitors who are looking for exactly what you offer.

A Balanced Approach: Check Your Logs First

Before making blanket decisions, take time to analyze your server logs. They reveal:

  • Which crawlers are visiting (via user agent strings like GPTBot, ClaudeBot, Google-Extended).
  • How often they hit your site (dozens, hundreds, or thousands of times per day).
  • Whether they bring referrals (some bots, like Perplexity, may drive traffic back to you).

Armed with this data, you can decide who to block, who to allow, and where to apply limits. For example:

  • Block crawlers on private or premium content.
  • Allow them on public sales pages where exposure could drive new leads.
  • Rate-limit or monitor bots that hit too aggressively.

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