Sébastien Balieu
Builder first, freelancer second.
I'm Sébastien, based in Brussels for over 10 years. Freelance full stack web developer, UX/UI designer, and founder of several companies. My specialty: ultra-fast websites, loading in under 1 second, 95+ on PageSpeed.
I co-founded Coddy, an urban escape game platform used by hundreds of thousands of players across 9 countries in Europe. With my co-founders, we raised funds, built teams, and ran the whole technical side, from the booking engine to automated content production.
After 4 years spent on automation and performance, I founded Numinam to bring the same approach to SMEs and startups: fast websites, AI automation, and custom internal tools, connected to each other. A showcase site with me: €3,500 to €7,000, delivered in 3 weeks to 3 months, response within 24 hours, and you keep full ownership of the code, domain and access.
What I do at Numinam
High-performance websites
Astro-based sites that load in under 1 second, score 95+ on PageSpeed, and are built for conversion and SEO from day one.
AI automation & workflows
n8n workflows, AI agents, and custom integrations that eliminate 10-20 hours of repetitive work per week for your team.
Custom internal tools
CRMs, dashboards, client portals: built around your actual processes, not the other way around. You own 100% of the code.
Background & expertise
Full stack development
10+ years building web applications. TypeScript, React, Node.js, Astro, Laravel, PostgreSQL. I choose the right tool for the job, not the trendy one.
UX/UI design
Every project starts with user intent. I design interfaces that convert because they follow how people actually use them.
International experience
Coddy operates in 9 countries. I've built multi-language, multi-currency platforms that scale across borders.
AI & automation
From GPT-powered workflows to fully automated lead qualification pipelines. I implement AI where it produces a measurable result, not where it makes a good demo.
Let's talk about your project
25 minutes. We review your website, processes, and tools. You walk away with a concrete action plan: free, no strings attached.