For two decades, SEO revolved around a handful of search-engine crawlers. Googlebot, Bingbot and their companions decided what content entered the index and how it ranked. That landscape has fundamentally changed. A new generation of AI crawlers—GPTBot (OpenAI), ClaudeBot (Anthropic), PerplexityBot, Google-Extended, Applebot-Extended, Meta-ExternalAgent and others—now traverses the web at scale, feeding large language models (LLMs) and AI-powered answer engines. Their objectives, behaviour and implications for publishers are profoundly different from anything we have dealt with before.

What are AI crawlers, exactly?

An AI crawler is an automated agent that downloads web pages to build or update the training datasets and retrieval indexes behind generative-AI products. Unlike traditional search bots, whose primary goal is to index pages for a search-results page, AI crawlers serve two distinct purposes:

1. Training data collection — harvesting text, code and media to train or fine-tune foundation models. GPTBot and ClaudeBot fall squarely into this category.
2. Retrieval-augmented generation (RAG) — fetching live content at query time to ground an AI answer in up-to-date sources. PerplexityBot and Google-Extended (when used for AI Overviews) operate here.

Some bots do both; the line is blurring. The critical takeaway is that AI crawlers may consume your content without ever sending a visitor back.

The major AI crawlers you should know

GPTBot (OpenAI)

Identified by the user-agent string GPTBot, this crawler gathers content for OpenAI's models and ChatGPT's browsing feature. OpenAI publishes an IP range list and respects robots.txt. Blocking GPTBot does not affect ChatGPT plugins that use their own browsing agents, which is worth noting.

ClaudeBot (Anthropic)

Anthropic's ClaudeBot collects training data for Claude models. Like GPTBot, it honours robots.txt and identifies itself transparently. Anthropic has stated it will respect opt-out signals.

PerplexityBot

PerplexityBot powers the Perplexity answer engine. It fetches pages in real time to generate cited answers. Because Perplexity surfaces inline citations and links, many publishers see it as closer to a search engine—and therefore more willing to allow it.

Google-Extended

Google introduced the Google-Extended user-agent token specifically to let site owners control whether their content trains Gemini and AI Overviews without affecting their regular Google Search indexing. Blocking Google-Extended in robots.txt has no impact on Googlebot or your SERP rankings.

Others to watch

• Applebot-Extended — Apple's token for AI training features in Apple Intelligence, separate from the main Applebot that powers Siri and Spotlight.
• Meta-ExternalAgent — Meta's crawler for AI training purposes.
• Bytespider — ByteDance's aggressive crawler. It claims to respect robots.txt, but publishers report high request volumes regardless.
• CCBot — the Common Crawl bot, whose open datasets are used by many AI labs.

How AI crawlers differ from search-engine bots

Understanding the differences is essential before you decide on a strategy:

• Value exchange. Search engines take your content and give back traffic. AI crawlers take your content and may give back nothing—or at best an indirect mention inside a generated response.
• Rendering depth. Most AI crawlers today perform shallow fetches (raw HTML) rather than full JavaScript rendering. This means server-side-rendered content is more exposed than client-rendered SPAs.
• Crawl patterns. AI crawlers tend to hit pages in bulk during training runs, causing traffic spikes. Search-engine bots crawl continuously and adjust rate based on server health.
• Directive support. All major AI crawlers respect robots.txt Disallow rules. However, finer directives like noindex, nofollow or nosnippet are search-engine concepts that most AI bots simply ignore because they do not maintain a public index.
• Legal framework. Search indexing has decades of legal and cultural precedent. AI training is still navigating copyright law across jurisdictions, making the question of consent and licensing far more charged.

The content-licensing question

The rise of AI crawlers has triggered a wave of content-licensing deals. Major publishers—news organisations, academic publishers, stock-photo libraries—have signed agreements worth hundreds of millions of dollars to allow (or restrict) their content in AI training sets. For smaller publishers the calculus is harder:

• If you block AI crawlers, your content is less likely to appear in AI-generated answers, potentially reducing a future traffic channel. But you protect your intellectual property and avoid the risk of AI-generated competitors parroting your work.
• If you allow them, you increase the chance of being cited in AI answers and you contribute to better, more accurate models. But you lose control over how your content is used and whether you receive attribution.

There is no universal right answer. The decision depends on your business model, content type and risk tolerance.

Impact on web traffic and SEO strategy

AI-powered search features—Google AI Overviews, Bing Copilot, Perplexity—are already displacing traditional organic clicks for informational queries. Studies show that AI Overviews can reduce click-through rates by 20-60% for queries where the AI answer fully satisfies user intent. This has several implications:

1. Transactional and navigational queries gain relative importance. Users still click when they want to buy, sign up or visit a specific site. Optimising for these intents becomes more valuable.
2. Being the cited source matters. When AI answers do include citations, those links receive disproportionate traffic. Structured data, authoritative content and brand recognition influence which sources get cited.
3. Content depth beats content volume. AI models are good at synthesising shallow content. Deep, original, experience-based content is harder to replicate and more likely to earn citations.
4. Technical SEO still matters—more than ever. If an AI crawler cannot access your page because of a misconfigured robots.txt, a server error or a rendering issue, you are invisible to the AI layer entirely.

Practical steps for 2026

1. Audit your current crawler access

Use Spider.es to check which AI crawlers can reach your content right now. The report shows the exact directive—robots.txt, meta robots or X-Robots-Tag—controlling each bot's access, so you can make informed decisions rather than guessing.

2. Set a deliberate policy per bot

Do not treat all AI crawlers the same. You might allow PerplexityBot (because it cites sources) while blocking Bytespider (because it does not). Add explicit rules to your robots.txt:

User-agent: PerplexityBot
Allow: /

User-agent: GPTBot
Disallow: /premium/
Allow: /blog/

User-agent: Bytespider
Disallow: /

3. Monitor crawl activity

Check your server logs regularly. Look for AI crawler user-agent strings, request volumes and the specific paths they target. Unexpected spikes may indicate an aggressive bot or an impersonator.

4. Strengthen your content moat

Invest in content that AI cannot easily replicate: original research, proprietary data, expert interviews, interactive tools and community-generated insights. This content retains value whether or not AI crawlers access it.

5. Stay current on legal developments

Copyright law around AI training is evolving rapidly. The EU AI Act, US fair-use rulings and national regulations are all in flux. What is permissible today may change tomorrow.

What about the robots.txt "AI" proposals?

Several proposals have emerged for a standardised way to communicate AI-specific permissions—extensions to robots.txt, new HTTP headers and even machine-readable licensing files. None has achieved universal adoption yet. For now, the most reliable approach is to use the bot-specific user-agent tokens that each AI company publishes and to block or allow them individually in robots.txt.

Final thoughts

AI crawlers are not a passing trend. They represent a structural shift in how content is discovered, consumed and monetised on the web. Ignoring them is no longer an option. Whether you choose to welcome them, restrict them or apply a nuanced policy per bot, the important thing is to make a conscious, informed decision.

Spider.es helps you see exactly which crawlers—traditional and AI—can access your content right now. Start with a report, build your policy, and revisit it regularly as the ecosystem evolves.