What Are AI Crawlers?

The Short Answer

For website owners who want visibility in AI-powered search, the important principle is:

Do not accidentally block the crawler responsible for the search experience you want to appear in.

At the same time, publishers may choose different policies for:

• search discovery
• model training
• AI grounding
• commercial crawlers
• private sections of the website

Crawler decisions should match the organization's actual objectives.

What Is a Web Crawler?

A web crawler is software that automatically requests webpages and discovers information across the web.

Traditional search engines have used crawlers for decades.

A crawler may:

• discover URLs
• fetch page content
• follow links
• detect changes
• build or refresh an index
• extract information for a particular product

Crawling itself does not guarantee ranking, citation or recommendation.

It makes content available for whatever system the crawler supports.

Crawler, Indexer and AI Model Are Not the Same Thing

These concepts are often mixed together.

Crawler

Fetches or discovers website content.

Index

Stores or organizes information so it can be retrieved.

Retrieval system

Finds relevant information for a query or task.

Model

Processes information and generates or evaluates outputs.

A crawler visiting a website does not automatically mean the page will be included in a generated answer or used to train a model.

The purpose of the crawler matters.

Not All OpenAI Crawlers Have the Same Purpose

One of the most important distinctions for publishers is between OpenAI search discovery and potential training use.

Two commonly discussed crawler controls are:

• OAI-SearchBot
• GPTBot

They should not be treated as interchangeable.

What Is OAI-SearchBot?

OAI-SearchBot is associated with discovery for ChatGPT Search.

OpenAI currently advises publishers that want public website content to be discoverable, surfaced and linked in ChatGPT search not to block OAI-SearchBot.

Allowing OAI-SearchBot does not guarantee:

• a citation
• a recommendation
• a top placement
• referral traffic

It improves eligibility for the content to be discovered for search.

What Is GPTBot?

GPTBot is separate from OAI-SearchBot.

OpenAI provides GPTBot controls for publishers that want to restrict their pages from potential model-training use.

This distinction is important.

A publisher may have different preferences for:

• appearing in ChatGPT Search
• allowing content to be used for potential model training

Do not assume that blocking GPTBot is equivalent to blocking ChatGPT Search.

Search discovery and model-training controls should be evaluated separately.

A Practical OpenAI Policy Example

A publisher might decide:

“We want our public articles to be discoverable in ChatGPT Search, but we do not want them available for potential training through GPTBot.”

Conceptually, that policy could allow:

OAI-SearchBot

while disallowing:

GPTBot

The exact robots.txt configuration should always be checked against OpenAI's current official crawler documentation before production changes are made.

Do not copy old crawler rules from random SEO articles without verification.

What Is Googlebot?

Googlebot is the crawler used for Google Search.

This remains important for Google's AI-powered Search experiences.

Google states that the normal SEO and crawling foundations used for Google Search also apply to generative features such as:

• AI Overviews
• AI Mode

Googlebot access therefore remains the relevant Search control.

There is not a separate requirement that a website must allow some special “AI Overview crawler” to appear in Google's AI Search features.

Google AI Search Uses Existing Search Foundations

Google's current guidance is especially important because it counters a common misconception.

Websites do not need a special AI file, AI schema or new crawler configuration simply to become eligible for AI Overviews or AI Mode.

The established Google Search fundamentals remain important:

• crawlability
• indexability
• useful content
• technical accessibility
• normal Search controls

Do not accidentally block Googlebot while trying to manage unrelated AI use.

What Is Google-Extended?

Google-Extended is a separate publisher control.

It is not a separate crawler making its own HTTP requests.

Google describes it as a robots.txt token publishers can use to manage certain uses of content Google already crawls.

Those uses can include:

• training future generations of Gemini models
• grounding in certain Gemini and Vertex AI experiences

Google also states that Google-Extended does not affect inclusion in Google Search and is not a Google Search ranking signal.

That distinction is important.

Googlebot vs Google-Extended

Think of them as different decisions.

Googlebot

Controls crawling for Google Search.

Blocking Googlebot can affect Search visibility, including Google's AI-powered Search experiences.

Google-Extended

Controls specified Gemini-related model-training and grounding uses.

Google states that this control does not determine whether the website appears in Google Search.

Publishers should therefore avoid treating the two user-agent controls as equivalent.

What Is PerplexityBot?

PerplexityBot is the crawler associated with Perplexity's search indexing.

Perplexity currently states that PerplexityBot respects robots.txt.

If a publisher blocks PerplexityBot, Perplexity says it will not index the full or partial textual content that has been disallowed.

Perplexity also notes that some limited information such as a domain, headline or brief factual summary may still be represented in certain circumstances.

Crawler policies can change, so publishers should review current official documentation when configuring access.

Does Perplexity Use Crawled Content for Foundation Model Training?

Perplexity currently states that PerplexityBot is used for indexing pages in a search-engine-like manner and that it does not use that content for foundation-model pre-training.

This is another example of why crawler purpose should be verified rather than assumed from the word “AI.”

What Is robots.txt?

robots.txt is a file located at the root of a website that provides crawling instructions to compliant automated crawlers.

It can specify different rules for different user agents.

Examples of crawler names may include:

• Googlebot
• OAI-SearchBot
• GPTBot
• PerplexityBot
• Google-Extended

However, robots.txt is a crawler-management mechanism.

It is not a security system.

robots.txt Does Not Make Content Private

A common mistake is using robots.txt to protect sensitive information.

Do not do this.

Private information should be protected using actual access controls such as:

• authentication
• authorization
• server permissions
• application security

A publicly accessible URL remains publicly accessible even if a crawler is asked not to crawl it.

Blocking Crawling Is Different From noindex

These controls can serve different purposes.

Crawl restriction

Asks the specified crawler not to fetch particular content.

noindex

Tells supported search systems not to include a page in their search index.

The interaction matters.

If a crawler cannot access a page at all, it may not be able to read an on-page noindex directive.

Always follow the documentation of the specific search system being controlled.

Google Preview Controls for AI Search

Google says website owners can use established Search preview controls to limit how information from pages appears in Search.

Depending on the desired outcome, controls can include:

• nosnippet
• data-nosnippet
• max-snippet
• noindex

These are normal Google Search controls rather than special AI-only markup.

Use them intentionally because restricting snippets can affect ordinary Search presentation too.

Should Businesses Block AI Crawlers?

There is no universal answer.

The correct decision depends on the business model.

A business seeking AI-search discovery

May prefer to allow relevant search-discovery crawlers.

A publisher concerned about model-training use

May choose to restrict specific training-related user agents while still permitting search discovery.

A private application

Should protect confidential content through real authentication rather than relying on robots.txt.

A commercial publisher

May have legal, licensing or content-strategy considerations beyond SEO.

Crawler policy is a business decision, not merely an SEO checkbox.

Do Not Use a Blanket “Block All AI Bots” Rule Without Understanding It

Some security tools provide a switch such as:

“Block AI crawlers.”

Before enabling it, determine exactly which user agents are included.

A broad rule might unintentionally block:

• search-discovery crawlers
• crawlers supporting products where the business wants visibility
• legitimate indexing

The label used by a CDN or security provider may not reflect the different purposes of individual bots.

CDNs and Firewalls Can Block Crawlers Too

robots.txt is not the only access layer.

A website may permit a crawler in robots.txt while still blocking it through:

• firewall rules
• bot protection
• CDN settings
• rate limiting
• hosting security
• IP restrictions

For example, OpenAI advises publishers who want ChatGPT search visibility to ensure that site infrastructure does not unintentionally block its published searchbot traffic.

If a crawler is allowed in robots.txt but never receives the page, discovery can still fail.

User-Agent Strings Can Be Spoofed

A request claiming to be a famous crawler is not automatically legitimate.

Malicious bots can copy a user-agent string.

For crawler verification, use the official verification methods supplied by the platform where available.

These may involve:

• published IP ranges
• reverse DNS
• official crawler documentation

Do not whitelist arbitrary traffic solely because the request says “Googlebot” or “GPTBot.”

Use Server Logs to Understand Crawling

Server logs can help identify:

• which crawlers visit
• which pages they request
• response status codes
• blocked requests
• crawl frequency
• unnecessary parameter crawling

This is useful when troubleshooting crawler access.

Do not confuse crawler visits with actual citations or rankings.

A crawl means the crawler requested the resource.

It does not prove the content was selected for a result.

Important Status Codes for Crawlers

Crawler access also depends on normal HTTP behaviour.

Examples:

200

The requested page is available.

301 or 308

The resource has moved permanently.

404

The page was not found.

410

The resource is intentionally gone.

5xx

The server failed to fulfil the request.

Persistent server errors can prevent reliable crawling regardless of robots policy.

JavaScript Rendering Can Affect Access

Modern websites may rely heavily on client-side JavaScript.

Important public information should remain technically accessible.

Server-rendered or otherwise reliably rendered content can reduce unnecessary dependence on client-side execution.

For AI SEO Experts Canada, the Next.js architecture intentionally favors server rendering and minimal client JavaScript for this reason as well as performance.

Should You Create an llms.txt File?

llms.txt has received attention as a proposed convention for helping AI systems understand websites.

However, website owners should not treat it as a universal requirement for AI-search visibility.

Support varies by platform.

Do not assume that creating one will cause:

• ChatGPT citations
• Google AI Mode visibility
• Gemini recommendations
• Perplexity citations

Core web accessibility, useful content and official crawler controls remain more important.

If AI SEO Experts Canada discusses llms.txt in future research, clearly separate proposed conventions from officially supported platform requirements.

Do AI Crawlers Need a Sitemap?

XML sitemaps can help search systems discover important URLs.

They remain useful for normal technical SEO.

However, a sitemap does not override robots.txt and does not guarantee:

• crawling
• indexing
• citation
• recommendation

Keep sitemap information accurate and limited to canonical URLs intended for discovery.

Crawler Access Does Not Equal AI Visibility

A common misconception is:

“We allowed OAI-SearchBot, therefore ChatGPT should recommend us.”

Crawler access only addresses one part of eligibility.

Visibility may also depend on:

• relevance
• content usefulness
• authority
• source quality
• current information
• query context
• broader web signals

Technical access is necessary in some systems but not sufficient for visibility.

Create a Crawler Policy Based on Business Objectives

A useful crawler-policy review can ask:

Search discovery

Which AI/search products do we want our public content to appear in?

Training

Are there model-training uses we want to allow or restrict?

Private areas

Which content should never be publicly accessible?

Infrastructure

Are firewall or CDN rules blocking legitimate crawlers?

Verification

Can we confirm important bot traffic is authentic?

Maintenance

Who reviews crawler rules when platforms change?

This produces a deliberate policy rather than an accidental one.

Illustrative robots.txt Strategy

A publisher might conceptually choose:

• allow Googlebot for Search
• allow OAI-SearchBot for ChatGPT Search discovery
• allow PerplexityBot for Perplexity indexing
• independently decide whether to allow GPTBot
• independently decide whether to allow Google-Extended

This is only an example of policy separation.

Do not automatically deploy this configuration to every website.

Always review:

• business goals
• licensing requirements
• current platform documentation
• security/CDN configuration

before modifying production robots.txt.

Review Crawler Rules Regularly

AI platforms change quickly.

Crawler policies that were accurate two years ago may no longer reflect current products.

Review important crawler rules periodically.

Useful events that may trigger review include:

• launch of a new AI-search product
• crawler-name change
• platform documentation update
• CDN/security migration
• unexplained traffic loss
• crawl errors
• major robots.txt changes

Avoid constantly changing rules without a reason.

Common AI Crawler Mistakes

Avoid:

• blocking every crawler with “AI” in its name
• assuming all OpenAI bots have the same purpose
• confusing Googlebot with Google-Extended
• treating robots.txt as security
• forgetting CDN or firewall blocks
• whitelisting spoofed bots by user-agent alone
• believing crawler access guarantees citations
• copying outdated robots.txt templates
• blocking Googlebot while attempting to manage Gemini training
• using noindex and crawl restrictions without understanding their interaction
• treating llms.txt as a universal ranking requirement

Crawler policy should be precise.

Frequently Asked Questions About AI Crawlers

What is an AI crawler?

AI crawler is a broad term for automated web systems associated with AI-related products. Different crawlers may support search discovery, indexing, training or other functions.

What is OAI-SearchBot?

OAI-SearchBot is associated with discovery for ChatGPT Search.

Is GPTBot the same as OAI-SearchBot?

No. OpenAI separates the search-discovery purpose of OAI-SearchBot from GPTBot controls related to potential training use.

What crawler does Google AI Mode use?

Google's AI features in Search rely on normal Google Search crawling foundations, including Googlebot.

Does blocking Google-Extended block Google Search?

Google states that Google-Extended does not affect inclusion or ranking in Google Search.

Does PerplexityBot respect robots.txt?

Perplexity currently states that PerplexityBot respects robots.txt directives.

Can robots.txt keep private content secure?

No. Use actual authentication and access controls for private information.

Does allowing an AI crawler guarantee citations?

No.

Do I need an llms.txt file?

It is not a universal requirement for visibility across major AI-search platforms. Follow each platform's official documentation rather than assuming a proposed convention is mandatory.

The Goal of AI Crawler Management

The goal is not to allow every bot or block every bot.

It is to understand the purpose of each crawler and make deliberate decisions.

For businesses seeking AI-search visibility:

Allow the search-discovery mechanisms that support the platforms you want to participate in.

For training or other uses:

Make a separate policy decision.

For private information:

Use real security.

That separation creates a much more sensible crawler strategy.

Continue Learning

ChatGPT Search

Understand how ChatGPT Search discovers and cites web content.

Google AI Mode

Learn how Google's AI-search experience explores web information.

Perplexity

Understand Perplexity search, citations and source visibility.