# Sébastien Fontaine

> Freelance senior developer based in Île-de-France (Paris region, France), working remotely across France, in French and English. Applied AI (LLM and AI agent integration, RAG, OCR, automation, local models), backend and infrastructure (Laravel, NestJS, AWS, Docker, GitLab CI, MySQL/PostgreSQL, observability), and SEO & GEO audits. 15 years of experience (since 2011), freelancing since 2018 as a French sole trader (EI). Also Senior AI Developer at HeyTeam since October 2023.

Key facts:
- Rates (excl. VAT): from €750/day (backend & DevOps), from €900/day (AI integration), SEO & GEO audit from €990 (full audit €2,500–3,500).
- Long-term client: Blue Margouillat, a 5-star Relais & Châteaux hotel in Saint-Leu (Réunion Island), for more than 10 years (hosting, maintenance, SEO & GEO audit in October 2026).
- Open source: Tabee: Tab Modifier, a Chrome extension with 70,000+ users (Chrome Web Store, January 2024) and 697 GitHub stars.
- Contact: hello@sebastienfontaine.me — https://sebastienfontaine.me/fr/contact

## Services

- [AI and LLM agent integration (FR)](https://sebastienfontaine.me/fr/integration-ia-agents): LLM features in existing products, AI agents, RAG, OCR, automation, local models, cost and latency control.
- [AI integration (EN)](https://sebastienfontaine.me/en/ai-integration)
- [Laravel, backend & DevOps (FR)](https://sebastienfontaine.me/fr/laravel-devops): Laravel applications and APIs, AWS, Docker, GitLab CI, SQL performance, production reliability.
- [Laravel & DevOps (EN)](https://sebastienfontaine.me/en/laravel-devops)
- [SEO & GEO audit (FR)](https://sebastienfontaine.me/fr/audit-seo-geo): visibility on Google and in AI assistants (ChatGPT, Gemini, Claude), audit and implementation, for SMEs, hotels and restaurants.
- [SEO & GEO audit (EN)](https://sebastienfontaine.me/en/seo-geo-audit)

## Case studies

- [Galactic Reigns](https://sebastienfontaine.me/en/work/galactic-reigns): real-time space strategy MMO; backend migrated from Laravel to NestJS by a chain of AI agents (spec, port, verify, adversarial review), with the old code as a golden-master oracle.
- [FuryBee](https://sebastienfontaine.me/en/work/furybee): self-hosted open-source platform, 35 containers run by one developer (Traefik, Cloudflare, Prometheus, Grafana, Loki).
- [Blue Margouillat](https://sebastienfontaine.me/en/work/blue-margouillat): 5-star hotel website, 10+ years of hosting and maintenance, full SEO & GEO audit.
- [AI agents for a development team](https://sebastienfontaine.me/en/work/ai-agents): Sentry alert to merge request agent, code review agent, performance monitoring with an investigation agent.
- [Afterfall Rising](https://sebastienfontaine.me/en/work/afterfall-rising): dark-fantasy RTS on Unreal Engine, in development, built with AI as a production tool.
- [Dictea](https://sebastienfontaine.me/en/work/dictea): open-source voice dictation desktop app in Rust.
- [Chrome extensions](https://sebastienfontaine.me/en/work/chrome-extensions): Tab Modifier, Disable CSP, Feedee.
- [Naburia](https://sebastienfontaine.me/en/work/naburia): online bookshop for AI-assisted books (Nuxt 4, PostgreSQL, Stripe).

## About

- [About (EN)](https://sebastienfontaine.me/en/about) · [À propos (FR)](https://sebastienfontaine.me/fr/a-propos)
- [CV (FR)](https://sebastienfontaine.me/fr/cv) · [CV (EN)](https://sebastienfontaine.me/en/cv)
- Profiles: [LinkedIn](https://www.linkedin.com/in/sebastien-fontaine-me/), [GitHub](https://github.com/sebastienfontaine), [Malt](https://www.malt.fr/profile/sebastienfontaine)