Work
Before advising you, I apply my methods to my own projects. Here are my main projects: a CMS, two SEO tools, two websites and a series of books, all public and verifiable.
Éclair CMS, the CMS built for Google and AI engines
I created Éclair CMS, an open-source PHP CMS with no database, designed for freelancers and small businesses. The archive weighs less than 900 KB, every page is served from a static cache, and SEO and GEO are built in without a single plugin: structured data, sitemap with hreflang, redirects, llms.txt, a Markdown version of every page and a live GEO score in the editor. This site runs on Éclair.
- 100/100 on all four Lighthouse scores and a time to first byte 1.6 times faster than WordPress with a caching plugin, according to public, reproducible benchmarks.
- Built-in AI assistant (Claude or ChatGPT) and MCP connector: the AI writes drafts, nothing is published without your click.
- WordPress migration without losing a URL with the free Eclair Export plugin: tested on 500 posts and 635 old URLs, zero 404 errors.
All the features of Éclair CMS
They all run on Éclair CMS: see the websites built with Éclair.
Arachnide SEO Spider
A free, open-source SEO crawler, an alternative to Screaming Frog. I designed, developed and published it on GitHub, and I keep improving it with feedback from the French-speaking SEO community. The report used to prepare this site was produced with Arachnide. What Arachnide does · View on GitHub
Vigie
An open-source AI visibility tracker, released in October 2026: it measures a brand's presence in AI assistant answers, question by question. View Vigie on GitHub
DelfOnline
An online platform for DELF, DALF and TCF exam preparation. I designed it, developed it with AI tools, launched it and optimized it for search on my own. delfonline.es
GustinAI
A website and AI training offering for businesses, designed from the outset to be cited by AI engines, in French, Spanish and English. gustinai.com
La Bible de Claude AI
A reference guide to Claude AI and an Amazon best-seller, published in six languages: French, Spanish, German, Italian, Portuguese and English, where it is titled The Claude AI Bible. View the book on Amazon
thierrygustin.com
This very website: moved from WordPress to Lovable, then to Éclair CMS, without losing a single URL (178 old URLs redirected in a single hop). Trilingual with reciprocal hreflang, served from a static cache, cookie-free, with complete structured data, an llms.txt and a Markdown version of every page for AI engines. View its source code: it's all there.
What about client case studies?
I only publish verifiable results, with my clients' consent. I'll show you concrete examples during our first call.
Have a project in mind?
Let's talk about your website and what AI engines say about you.