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Thierry Gustin

GEO & SEO Consultant: Get Your Business Cited by AI

Your customers are asking ChatGPT, Perplexity, Gemini, Claude and Google's AI Overviews. I make sure the answers mention your business, with a measurable method and tools I built myself.

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  • In search since 2011 [1][1] Thierry Gustin's LinkedIn profile
  • Creator of Arachnide SEO Spider and Vigie, two open-source tools [2][2] GitHub repositories of Arachnide SEO Spider and Vigie
  • Author of La Bible de Claude AI, an Amazon best-seller, also published in English as The Claude AI Bible [3][3] The Claude AI Bible on Amazon
  • 30,000+ followers on LinkedIn [1][1] Thierry Gustin's LinkedIn profile

Which real estate agency would you recommend to sell an apartment in Madrid?

Here are three agencies often recommended for selling an older apartment in Madrid. The first, Your Agency, publishes detailed neighborhood estimates and verified client reviews. The other two are mostly cited by directories and local media.

Illustration. The goal of GEO: your site becomes the cited source.

Your customers no longer search only on Google

A growing share of searches end in an AI-written answer, often without a click to any website. If your business isn't cited in that answer, it doesn't exist for that customer.

  • ChatGPT has 900 million weekly users. [4][4] OpenAI, figure announced on February 27, 2026, reported by TechCrunch
  • Google's AI Mode has passed 1 billion monthly users. [5][5] Sundar Pichai, Alphabet Q2 2026 results, July 22, 2026
  • When Google shows an AI-generated summary, users click a classic link in 8% of visits, versus 15% without a summary. [6][6] Pew Research Center, July 22, 2025, browsing of 900 US adults in March 2025
  • 48% of French people aged 12 and over use generative AI, up 15 points in one year. [7][7] Arcep and CREDOC, Baromètre du numérique, 2026 edition, published February 9, 2026 (June 2025 survey)
  • 37.9% of Spaniards aged 16 to 74 used a generative AI tool in the last three months. [8][8] INE, Encuesta sobre equipamiento y uso de TIC en los hogares 2025, November 20, 2025

SEO remains the foundation. GEO adds the layer that turns your site into a source AI engines reuse.

What is GEO?

GEO (Generative Engine Optimization) covers the techniques that increase the likelihood of an AI answer engine (ChatGPT, Perplexity, Gemini, Claude or Google's AI Overviews) citing your site, your brand or your products. It builds on SEO, which makes your pages crawlable and indexable, and adds three requirements: content that's easy to extract, a clear and consistent entity, and evidence confirmed by other sources.

SEO and GEO in brief
SEOGEO
GoalRank your pages in the resultsBe cited in the generated answer
What you measureRankings, clicks, trafficCitations, brand mentions, share of voice in AI answers
Main leversTechnical, keywords, linksDirect answers, sourced evidence, consistent entity, mentions on other sites

Read the complete GEO guide

Three ways to work together

  • GEO Audit

    Know what AI says about you, who gets cited instead of you and what to fix first.

    from €300 excl. VAT

    Discover the GEO audit

  • AI Search Optimization

    A monthly service to become a source ChatGPT, Perplexity and Google cite.

    from €800 excl. VAT per month

    Discover the monthly service

  • GEO Training

    A hands-on day to make your team autonomous in AI search optimization.

    from €1,500 excl. VAT per day

    Discover the training

Need a solid technical foundation first? Discover my SEO consulting work.

See all pricing

How I make a business citable by AI

My method follows five steps, from initial measurement to monthly monitoring. Each step produces a concrete deliverable.

  1. Measure

    I test the questions your customers actually ask in ChatGPT, Perplexity, Gemini, Claude and Google, and record who gets cited.

  2. Fix the technical base

    crawling, indexing, HTML rendering, speed, structured data, AI crawler access. I fix whatever prevents engines from reading your site.

  3. Make your content citable

    direct answers, definitions, sourced figures, tables, FAQs. I rewrite the pages that matter in the format AI engines reuse.

  4. Build authority

    consistent profiles, mentions on reference sites, client reviews. AI engines more readily repeat what other sources confirm.

  5. Monitor and adjust

    every month, I re-measure the same questions and show you what moved, with evidence.

My evidence is public

I'm not asking you to take my word for it. Here's what I've built, in open access.

See all my work

Who is Thierry Gustin?

Portrait of Thierry Gustin, GEO and SEO consultant in Madrid

I've worked in search since 2011 and as an independent since 2014, between France and Spain, from Madrid. My path has been anything but linear: optician, WordPress and SEO consultant, chef, then author and tool builder. Today I run several activities on my own, with AI as my team. That hands-on experience is what I put to work for your visibility.

Discover my background

Is your website ready for AI?

Answer 10 questions and get your GEO readiness score in 2 minutes, with the three priority actions.

Take the free check

Frequently asked questions about GEO

What's the difference between SEO and GEO?
SEO aims to rank your pages in Google's results. GEO aims to get your brand cited in AI-generated answers. The two complement each other: a poorly crawled or poorly indexed page is unlikely to be cited, and a well-ranked page isn't necessarily picked up by an AI if it doesn't answer the question clearly.
How long does it take to get cited by ChatGPT or Perplexity?
Engines that search the web in real time, like Perplexity, ChatGPT with search or Google's AI Overviews, can pick up a page as soon as it's crawled and indexed, sometimes within a few weeks. Presence in a model's internal knowledge depends on its training cycles and takes longer. I measure both separately.
Can anyone guarantee appearing in AI answers?
No. Nobody controls an AI model's answers, and any promise of guaranteed results should raise a red flag. I commit to a method, documented actions and an honest measurement of how your visibility evolves.
How much does a GEO audit cost?
My GEO audit starts at €300 excl. VAT for a single-language brochure site. The price depends on the number of pages, languages and questions to test. You receive a fixed quote after a 30-minute call.
Do you work in France and Spain?
Yes. I'm based in Madrid and work in French and Spanish for companies in both countries, remotely, or on-site for training.
Do you need an llms.txt file to be visible in AI?
It's not essential. Google states that no special file or markup is required to appear in its AI features. An llms.txt doesn't hurt and may help some tools, but it's no substitute for a well-crawled site, clear content or a recognized brand. [9][9] Google Search Central, “AI features and your website”

All questions

Find out what AI says about your business

In 30 minutes, I'll live-test a few key questions from your market across the main AI engines and tell you where to start. No commitment.

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Sources

  1. [1] Thierry Gustin's LinkedIn profile (opens in new tab) ↩
  2. [2] GitHub repositories of Arachnide SEO Spider and Vigie (opens in new tab) ↩
  3. [3] The Claude AI Bible on Amazon (opens in new tab) ↩
  4. [4] OpenAI, figure announced on February 27, 2026, reported by TechCrunch (opens in new tab) ↩
  5. [5] Sundar Pichai, Alphabet Q2 2026 results, July 22, 2026 (opens in new tab) ↩
  6. [6] Pew Research Center, July 22, 2025, browsing of 900 US adults in March 2025 (opens in new tab) ↩
  7. [7] Arcep and CREDOC, Baromètre du numérique, 2026 edition, published February 9, 2026 (June 2025 survey) (opens in new tab) ↩
  8. [8] INE, Encuesta sobre equipamiento y uso de TIC en los hogares 2025, November 20, 2025 (opens in new tab) ↩
  9. [9] Google Search Central, “AI features and your website” (opens in new tab) ↩