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AI search optimization: how to get cited by ChatGPT and Google AI

AI search optimization means making your pages reachable and quotable by AI answer systems. Google says its AI features run on the same ranking systems as ordinary Search, so most of the work is ordinary SEO. Three things differ: non-Google crawler access, citation-dense writing, and a report that counts impressions rather than clicks.

Francisco Contreras

Francisco Contreras · Founder, Machina

12 min read

Abstract liquid-glass render: a spray of aqua glass filaments fanning out from a gold glass disc into a constellation of small green glass nodes, on a near-black background.

Key takeaways

  • Pew Research watched 68,879 Google searches by 900 US adults in March 2025. An AI summary appeared on 18% of them, and clicks to a search result roughly halved: 8% of visits against 15%.
  • An AI citation behaves more like a billboard than a click. Users clicked a link inside the AI summary on 1% of visits to a page that showed one.
  • The peer-reviewed evidence points at writing, not markup. Adding cited sources, quotes and statistics raised visibility in AI answers by 30 to 40%, while keyword stuffing scored below changing nothing.
  • llms.txt has no evidence behind it. Ahrefs logged 137,210 domains and found that 97% of llms.txt files got zero requests in May 2026, and Google says that Search does not use them.
  • Search Console added Generative AI performance reports on June 3, 2026. They count impressions in AI Overviews and AI Mode, not clicks, and they are still rolling out to a subset of sites.

What is AI search optimization?

For one month in 2025, Pew Research watched what 900 American adults did with Google. Across 68,879 searches, 18% returned an AI summary. When one appeared, people clicked a search result on 8% of visits. When it did not, they clicked on 15%. Ahrefs found the same effect from the publisher's side, putting the click loss to the top-ranking page at 34.5% across 300,000 keywords.

AI search optimization is the work of staying visible when the summary is the answer. It covers Google's AI Overviews and AI Mode, plus ChatGPT, Perplexity, Copilot and Gemini, which run their own crawlers and their own indexes.

Most of the advice written about it is older than the docs. Google's May 2026 guide to optimizing for AI features devotes a section to the things you do not need to do. It names answer engine optimization and generative engine optimization, then knocks down llms.txt files, content chunking, AI-specific rewriting and bought mentions.

1%

Visits to a page with an AI summary where the user clicked a link inside it.

Pew Research Center, browsing data from 900 US adults, March 2025

Set your expectation before you spend. A citation puts your name in front of somebody who is deciding, and it rarely sends a click. Judge it on inquiries, not on sessions.

How is this different from ordinary SEO?

Less than the category name suggests. Google says its AI features run on the core Search ranking and quality systems, and that there are no additional requirements to appear in them. A page Google cannot index is a page Google cannot sum up, so ordinary technical SEO still comes first.

Six differences are worth knowing, and most of them sit outside Google.

Where AI search optimization departs from classic SEO.
The jobClassic SEOAI search optimization
Crawler accessAllow GooglebotAllow Googlebot, OAI-SearchBot and PerplexityBot separately
Ranking systemGoogle core ranking systemsSame systems drive AI Overviews and AI Mode
Page formatTitles, headings, internal linksSame, plus inline citations, quotes and statistics
Structured dataEarns rich results in SearchNo special schema needed for AI features
Snippet controlsLimits search preview lengthnosnippet and max-snippet:0 remove AI eligibility
Success metricClicks and positions in Search ConsoleImpressions only, in the Generative AI report

Sources: Google Search Central on generative AI features (May 2026); OpenAI and Perplexity bot docs; the GEO paper at KDD 2024. Full links below.

Which index each assistant queries decides who is even in the running. We covered that plumbing in a separate article on how AI assistants choose sources, and Google's two surfaces get their own guide. This one stays on execution.

Which crawlers decide whether AI can see you?

Start at the firewall, because this part is binary and the platforms document it themselves. OpenAI runs three agents, and owners often block the wrong one. GPTBot collects training data, OAI-SearchBot surfaces sites in ChatGPT search, and ChatGPT-User fetches a page on request. OpenAI says sites opted out of OAI-SearchBot will not be shown in ChatGPT search answers.

Blocking GPTBot to keep your writing out of a training run is a fair call. Block every OpenAI agent to get there and you also drop out of ChatGPT search answers, with no error message. Perplexity draws the same line: PerplexityBot indexes pages for search and is not used for model training.

The six user agents worth knowing, and what blocking each one costs.
AgentWhat it doesBlock it and you lose
GooglebotCrawls for Google Search, which feeds both AI surfacesGoogle Search plus both AI surfaces
GPTBotCollects data for OpenAI model trainingNothing in ChatGPT search answers
OAI-SearchBotSurfaces sites inside ChatGPT searchYour place in ChatGPT search answers
ChatGPT-UserFetches a page on requestLive fetches during a chat
PerplexityBotIndexes pages for Perplexity search, not model trainingYour listing in Perplexity answers
Perplexity-UserAnswers a live request and ignores robots.txtLittle, since a person triggers it

Sources: OpenAI and Perplexity bot documentation; Google Search Central on AI features. Checked August 2026.

Cloudflare compared May 2024 with May 2025 and found Googlebot's share of crawler requests up from 30% to 50%, GPTBot up from 2.2% to 7.7%, and ClaudeBot down from 11.7% to 5.4%.

Two settings can remove you without anyone touching robots.txt. Google says that nosnippet, data-nosnippet, max-snippet and noindex set your display preferences, and that stricter ones limit how AI features can use your content. A max-snippet of zero, left on a template after an old scraping scare, blocks every page built on it. Google also asks that a site be included in Search generative AI features in Search Console.

The crawler audit, in about an hour

What makes a page citable?

The strongest evidence here is a paper rather than a blog post. Researchers built GEO-bench, 10,000 test queries across 25 subject areas, tried nine ways of editing a page against an unedited control, and published the results at KDD 2024. The winning edits were adding direct quotes, adding statistics and citing sources, which the paper puts at a 30 to 40% relative gain.

  • Add quotations27.2
  • Add statistics25.2
  • Cite sources24.6
  • No changes (baseline)19.3
  • Keyword stuffing17.7
Higher is better. Keyword stuffing was the only edit scoring below leaving the page alone.Aggarwal et al., "GEO: Generative Engine Optimization", KDD 2024, Table 1 (position-adjusted word count, overall).

Two results deserve a place on the wall. Keyword stuffing scored 17.7 against a do-nothing baseline of 19.3, so it left pages less visible than leaving them alone. Edits to fluency and reading level, which change no facts, lifted visibility by 15 to 30%. Tested on Perplexity, a live engine, the same methods lifted visibility by up to 37%.

That reads like an editing brief, so treat it as one.

The citable-content checklist

Google puts the same idea above every other step in its guide: pages built on what you have seen and done. Local firms should keep the Google Business Profile current too, since Google feeds it into AI answers about local businesses.

Does llms.txt help?

No evidence says it does. Jeremy Howard proposed llms.txt in September 2024 as a plain-text file telling AI systems where a site's important content lives. The proposal claims no adoption by any AI company.

The field data is worse than that modesty suggests. Ahrefs read server logs across 137,210 domains and published the numbers in June 2026. Of those domains, 28% publish an llms.txt file, and 97% of the files got zero requests in May 2026. AI retrieval bots, the only kind that could cite you, made up 1.1% of the AI bot requests to files that got any traffic. The study also found zero requests from AI bots for llms.txt files that do not exist, so the systems never check for one. Google says Search does not use llms.txt or any other special machine-readable file.

How do you measure AI citations today?

Three layers exist, and the first two are free. Google Search Console launched Generative AI performance reports on June 3, 2026, showing impressions in AI Overviews, AI Mode and Discover by page, country, device and date. Read the caveats with the numbers: impressions and not clicks, more metrics promised over time, and a rollout that reached a subset of sites first.

The second layer is GA4, where you segment referrals from chatgpt.com, perplexity.ai, gemini.google.com and copilot.microsoft.com. Several assistants strip the referrer, so treat that figure as a floor. Our GA4 reference build covers the setup. The third free layer is your own server logs, the only place that confirms a crawler reached a page.

What each measurement layer tells you, and what it costs.
LayerWhat it answersPrice
Google Search ConsoleImpressions in AI Overviews, AI Mode and Discover, by pageFree
GA4 referral reportsSessions arriving from chatgpt.com, perplexity.ai and geminiFree, and undercounted
Server or CDN logsWhether OAI-SearchBot and PerplexityBot reached the pageFree to low
Prompt tracking, entry tierWhich tracked prompts mention youFrom about $29/mo for 15 prompts
Prompt tracking, program tierWider engine coverage plus content toolingAbout $99 to $399/mo
Agency monitoring platformsBrand visibility across AI engines and social$398 to $699/mo

Search Console scope from Google Search Central (June 3, 2026). Prices from vendor pricing pages (Otterly.AI, Profound, Ahrefs Brand Radar), checked August 2026.

Before any of that, take a baseline you did not pay for. Our free SEO report scores any URL on ten weighted on-page signals as an AI Visibility Score, beside Core Web Vitals and the usual checks. It reads your page. It cannot see whether ChatGPT cited you last Tuesday, and no on-page tool can.

Paid prompt trackers answer a different question: which of your buying questions surface you, and who gets named instead. Work the free layer first, then decide whether a monthly tracker earns its line in the budget. Checked every month rather than once, that becomes a standing program, which is the shape our AI visibility service takes.

What should you skip?

The list of things not to do is short, well documented and expensive to ignore.

  • Keyword stuffing for AI, which the KDD 2024 benchmark measured at 17.7 against a 19.3 baseline for changing nothing.
  • Chopping pages into fragments, since Google says there is no requirement to break content into tiny pieces.
  • Rewriting in a stiff AI-friendly voice, since Google says you do not need to write a specific way for AI search.
  • Buying mentions, which Google calls inauthentic and less helpful than it might seem.
  • Making a page for every question variant, which Google says breaks its scaled content abuse spam policy.
  • Treating schema markup as a citation lever, since Google says there is no special structured data you need to add for AI features. Keep your schema accurate because it earns rich results in ordinary search.
  • Buying a monitoring platform at several hundred dollars a month before anyone has read your robots.txt file. A tool reports that you are missing, not that a firewall rule is why.

Where should you start this month?

Run it in this order, because the cheap work gates the expensive work.

  1. Audit crawler access and snippet settings. One hour, and it decides whether anything else counts.
  2. Turn on the Generative AI performance report in Search Console and write down the number you start with.
  3. Edit your ten best pages against the checklist above: sources named, numbers dated, answers first.
  4. Baseline ten to twenty buying questions. Run them through ChatGPT and Perplexity monthly and record who gets named.
  5. Fix the structure and reading level of those pages, worth 15 to 30% in the benchmark.
  6. Publish what no competitor can copy: your own numbers, your own jobs, the case that went sideways.

Pew's 900 adults clicked a link inside an AI summary on 1% of the visits where one appeared. Work through that list and you should show up in more summaries while your traffic line barely moves. Ask each new caller where they heard about you, keep the answers for a quarter, and read them beside the impression count.

FAQ

Frequently asked questions

What is AI search optimization?

It means making your business reachable and quotable by AI answer systems: Google's AI Overviews and AI Mode, plus ChatGPT, Perplexity, Copilot and Gemini. It overlaps almost entirely with good SEO. Google states there are no additional requirements to appear in its AI features. What differs is crawler access for the non-Google assistants, and pages that are easy to quote.

Is generative engine optimization different from SEO?

Mostly no, at least for Google. Its May 2026 guide says the AI features run on the core Search ranking systems, and it names answer engine optimization and generative engine optimization in a section that knocks down their tactics. One difference is real: ChatGPT and Perplexity run their own crawlers, and allowing Googlebot does not cover them.

Does llms.txt help you get cited by AI?

No evidence says it does. Ahrefs studied server logs across 137,210 domains and found 97% of llms.txt files got zero requests in May 2026, and that AI bots never request the file from sites without one. Google says Search does not use them. Publish one if you like, but pay nobody for it.

How do I show up in ChatGPT?

Allow OAI-SearchBot in robots.txt and at your firewall. OpenAI says sites opted out of it will not be shown in ChatGPT search answers. It is a different agent from GPTBot, which handles model training, so you can block training and keep search visibility. Then make sure your best pages are indexed and easy to quote.

How do I measure AI citations?

Three layers, cheapest first. Search Console's Generative AI performance reports, launched June 3, 2026, show impressions in AI Overviews and AI Mode, free and first-party, though still rolling out to a subset of sites. GA4 referral tracking for chatgpt.com and perplexity.ai is free but undercounts, because some assistants strip the referrer. Prompt trackers start around 29 dollars a month.

Will being cited in AI answers send me traffic?

Rarely, and you should plan for that. Pew found users clicked a link inside an AI summary on 1% of visits to pages that showed one. A citation is closer to a billboard than a click: your name in front of somebody at the moment they decide. Judge it on inquiries, not sessions.

Sources

  1. Google Search Central, "Optimizing your website for generative AI features on Google Search" (May 2026), including the section on what you do not need to do
  2. Google Search Central, "AI features and your website", the source of "no additional requirements ... nor other special optimizations necessary"
  3. Google Search Central Blog, "Introducing Search generative AI performance reports in Search Console" (June 3, 2026)
  4. Google Search Central Blog, "Top ways to ensure your content performs well in Google's AI experiences on Search" (May 21, 2025), on snippet and preview controls
  5. Pew Research Center, "Google users are less likely to click on links when an AI summary appears in the results" (July 22, 2025), browsing data from 900 US adults across 68,879 searches in March 2025
  6. Aggarwal, Murahari, Rajpurohit, Kalyan, Narasimhan and Deshpande, "GEO: Generative Engine Optimization", KDD 2024, the GEO-bench study of 10,000 queries across 25 domains
  7. Ahrefs, llms.txt adoption study across 137,210 domains (June 15, 2026), server-log evidence
  8. Ahrefs, "AI Overviews reduce clicks by 34.5%", a controlled study across 300,000 keywords
  9. OpenAI, bots and crawlers documentation: GPTBot, OAI-SearchBot and ChatGPT-User
  10. Perplexity, bots documentation: PerplexityBot and Perplexity-User
  11. llmstxt.org, the original llms.txt proposal, published September 2024
  12. Cloudflare, "From Googlebot to GPTBot: who's crawling your site in 2025", on crawler share from May 2024 to May 2025
  13. Google Search Console: the Generative AI performance report lives under Performance
  14. Otterly.AI, public pricing for prompt-level AI citation monitoring, checked August 2026
  15. Profound, public pricing for AI visibility monitoring and AEO tooling, checked August 2026
  16. Ahrefs, public pricing for Brand Radar AI visibility tracking, checked August 2026

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