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Twenty years of digital marketing, web and mobile development and entrepreneurship.

I’m Sébastien Balieu. I’ve worked in-house, run an agency, co-founded a startup and raised funding. Today, I help businesses get their growth moving.

Portrait of Sébastien Balieu

Sébastien Balieu

Growth Partner, Brussels

Let’s meet More about my background
Sébastien Balieu by the sea

These days, even my mum can build a website.

For a long time, building a digital product was hard. Fewer people could do it, which made it easier for a well-built product to find its market.

AI and no-code tools have lowered that barrier. More entrepreneurs can launch a website, an app or a service, and supply is growing faster than demand.

Building the product is no longer enough. You need to find the people who need it and give them a reason to use it. That’s where I focus my work with entrepreneurs: acquiring customers first, then improving usage and revenue.

Sébastien Balieu smiles while hiking, mountain in the background
His companion photographs the gorges from a rock

I wrote my first line of code at 8 years old, before becoming an electrician, marketer then entrepreneur.

I was born in 1984. I discovered programming in BASIC on a Thomson TO7 and built my first websites in 1998. I went on to train as an electrician, then moved into digital marketing and started my own business in 2015.

Along the way, I learned how to turn an idea into an MVP, find customers, build a product and keep people coming back.

Today, I use that experience to help businesses grow.

Sébastien Balieu, perplexed, holds the box of the game “OK Boomer!” »
Selfie of Sébastien Balieu hiking in front of a rocky summit

Experience helps me see what’s getting in the way.

I’ve been a marketing manager, a service provider and a business owner. I understand the targets you need to hit and the constraints that make them hard to reach.

2006

AvantageGolf

Digital Marketing Manager

We built one of France’s first golf e-commerce platforms when nobody wanted one. I did business between London and Paris without ever having played a full 18 holes.

2009

Walibi (CDA Parks)

Digital Marketing Manager

I led Walibi’s digital transformation in Belgium, France and the Netherlands, along with e-commerce for several parks. Its Facebook page became Belgium’s largest by fan count.

2014

Zetes

Digital Marketing Manager

I moved into B2B, working on customer acquisition and marketing automation for major accounts. Then came a website redesign across 17 countries, 8 languages and more than 1,000 pages.

2016

One More Pixel

Founder and developer

I started my agency in Brussels, delivering websites and business applications. I learned that a poorly scoped project gets complicated long before development starts.

2018

Kalio Tech

Co-founder and developer

One More Pixel became Kalio, a web and mobile agency I co-founded with Didier Boulvin and Stéphane Draux. It was my first development team.

2020

Coddy

Co-founder and CEO

With my partners at Kalio, we launched Coddy, our urban escape game platform. The company raised funding in 2022 and expanded to more than 70 cities across Europe.

2025

Numinam

Growth Partner

I now use that experience to help entrepreneurs and SMEs improve acquisition, conversion and their ability to get things done.

Tomorrow

Your business next?

Consultant and partner

Tell me about the project you want to build. I’ll help you take it from an idea to launch, then find customers and keep them coming back.

Contact me

I work alongside my clients.

Here’s what they say about working with me.

Valérie Van Belle.

Valérie Van Belle.

Managing director • Euronet

Numinam (One More Pixel) is doing a fantastic job for Euronet. They’ve started the mission in saving our web-site from a cyber-attack. We had lost a lot of information and they had to rebuild our web-site. They had to recover the data left on our former server… that was a huge mission and they did it in a very professional way. Currently, they do our website maintenance and are assuring the security and the integrity of our website. Numinam is proactive and very reactive when we have to face a problem. Moreover, we’ve started collaborating on our SEO… also a huge mission… We wanted to improve our web visibility and after 3 months, we’ve started seeing the positive results. Mission seems to be very promising.
Jérôme Van De Sande

Jérôme Van De Sande

Product & Data Leader • Heat Me

Numinam's technical and design vision has enabled us to improve our lead generation flows. A big step forward.
Didier Boulvin

Didier Boulvin

Coddy

Sébastien is always attentive and understood our needs perfectly when it came to redesigning our website! The new site looks great and was delivered on time. We've already gained a few customers thanks to the improved SEO of the new site
Stephane Draux

Stephane Draux

Founder • Spengo

Numinam's contribution to the development of our App has been significant in its success with our B2C and B2B customers.
Jean Verheyen

Jean Verheyen

CEO • Nallian

At Nallian we build solutions that are trusted by the world's leading airports, ground handlers and logistics companies. But our website no longer reflected that level of excellence. This redesign ensures our first impression matches the quality of what we actually deliver.
Joke Aerts

Joke Aerts

Director of Marketing • Nallian

The new website much better reflects who we are. It tells our story more clearly, it's easy to navigate, it looks fresh and modern. It is more Nallian.
Olivier Lafosse

Olivier Lafosse

Founder & CEO • Heat Me

Numinam has completely modernized our website. The design is clearer, more credible, and our visitors understand what we do. A real leap in quality. Also worth noting is the excellent collaboration between Numinam and our development agency. Thank you!
Shirley Boterdael

Shirley Boterdael

Marketing & Com. Manager • Highcodata

It was a real pleasure to do business with Sebastien. He did a great job and transform our inefficient and boring website to a nice one that generate leads. Moreover, Sebastien is a patient and reliable partner and he's always ready to help.

Let’s move your project forward together.

Tell me what you have in mind and what’s getting in the way. We’ll work out where to start. When we work together, you deal directly with me, from our first conversation through to the results.

Let’s talk about your project
  1. 01

    A clear priority

    I start by finding what’s holding your results back. You’ll know what needs attention now and what can wait.

    A clear reason for each decision

  2. 02

    I do the work myself

    I build what I recommend, whether it’s a page, an automation or a tool. The person doing the work already understands why it matters.

    One person to work with

  3. 03

    We track the results

    We agree on what to measure before we start. Once the work is live, we review the results together and decide what comes next.

    We agree on a metric from the start