In a world where technologies are evolving at high speed, the IT department (DSI) must reinvent itself to better support the company’s strategy. Today, we’re joined by Sébastien to discuss the key challenges, issues, and best practices that help an IT department transform effectively. Let’s dive right in !
About Sebastien Louyot
Sebastien Louyot has over 25 years of experience in IT, with a career shaped by roles as CTO and CIO. He played a key role in establishing the IT department at Doctolib before joining Altavia, a French mid-sized company, to support its digital transformation. His expertise spans IT architecture, technological innovation, and the implementation of digital strategies that drive business growth.
CIO of Altavia
Introduction
Ismaïl : Sébastien, can you introduce yourself ?
Sebastien : Hello Ismaïl, hello everyone! Thanks for the opportunity and this great moment of exchange.
My journey can be broken down into three major phases :
- First phase: I started in technology infrastructure, mainly in the telecom sector, in the late ’90s right in the middle of the Internet boom.
- Second phase: I went on to create several companies: a telecom operator, followed by an IT services firm.
- Third phase: For the past twelve years, I’ve been working as a CIO. I began as an independent consultant (interim CIO, part-time CIO) before joining Doctolib in 2019, during a phase of hypergrowth especially during the Covid crisis.
Today, I’m the CIO at Altavia, a group specialized in designing and executing marketing campaigns for the retail sector, where I’ve been working for nearly a year and a half.
Why transform the IT department (DSI) ?
Ismaïl : You’ve led ambitious IT transformation projects, both at Doctolib and now at Altavia. So let’s start with a simple question: why? What pushed you to make changes in your organization?
Sebastien : First of all, you don’t transform an IT department just for the sake of it you transform it because the company’s strategy demands it. In other words, if the IT department can’t support the company’s goals over the next three to five years, it’s time to act.
At Doctolib, for instance, the IT team had barely a dozen people for 800 employees. We were already anticipating strong growth, but then COVID hit and our needs exploded: more equipment to deploy, greater resilience to build, operational performance to optimize… We had to evolve from a small local support team into a full-fledged IT department capable of supporting hypergrowth.
At Altavia, the context is different, but the challenges are similar. The organization is older, with a significant technological legacy many in-house applications that no longer fit the group’s new vision. Altavia wants to reinvent itself and evolve its model, but the IT systems aren’t keeping up. So we need to modernize the infrastructure, data, cybersecurity, and applications, while also reshaping the team to bring in the right skills. Once again, it all starts with a clear strategic need and a strong desire to support the company’s transformation.
Adapting your IT department posture
Ismaïl : So does that mean you’re not the same CIO at Doctolib as you are at Altavia even though you’re the same person?
Sebastien : You could almost call it “schizophrenia,” but in reality, I’m not the same CIO from one company to another. I stick to my core values collaboration, agility, a hands-on mindset but I have to adapt my posture.
At Doctolib, we operated in a highly tech-driven environment, already geared toward performance and hypergrowth. Scaling up quickly came more naturally.
At Altavia, there’s a strong IT legacy and a mix of team members some have been around for a long time, others are just arriving. You have to accept that transformation takes more time and can be more complex, because things weren’t designed with digital in mind from the start. Here, the challenge isn’t just to “modernize” the IT department, but to truly lead change management and bring everyone on board at the same pace.
A transformation linked to the needs of the company
Ismaïl : So basically, you decided to transform your IT department because the company itself is undergoing transformation is that right ?
Sebastien : Exactly. As soon as there’s a strong strategic shift in the company, the IT department must adapt. If the organization isn’t undergoing any major change, there’s not really a “reason” to transform the IT department. Like we said, you don’t transform for fun you do it because the company will need new IT capabilities in three years, and it’s the CIO’s job to start building them now. If the transformation is driven solely by IT, without considering how the business is evolving, it risks being disconnected from reality and failing to address the organization’s real challenges.
How to transform ?
Ismaïl : Thanks Sébastien. Now that you’ve explained why to transform an IT department, can you walk us through the how? Very often, companies start with a simple org chart change, but don’t really address how the IT department actually operates. What’s your take ?
Sebastien : It’s not just about the org chart. Of course, sometimes you need to adjust the structure and hire new talent, but the transformation has to be global a full 360°.
- Organization & Team : First, you need to ask : “What kind of organization do we need to support the company’s strategy?” Sometimes, you already have people on the team who can grow into new roles; sometimes you don’t and that’s when you need to recruit externally. The goal is always to build the most relevant team, with the right balance between coordinators and hands-on contributors.
- Culture & Ways of Working : Culture is a major pillar of transformation. It’s not just about replacing people, it’s about changing habits and mindsets. For example, I expect my teams to take full ownership of their topics, to take initiative, and to raise the flag when something’s not working. To make that happen, the CIO has to embody those values, lead by example, and encourage behaviors that move the organization forward.
- Methodology & Technology : Work methods (collaboration, reporting, agility, etc.) and the chosen tech stack play a critical role. You need a clear roadmap and a clear process for implementing each change. Personally, I prefer an iterative approach over a big bang, it avoids destabilizing the teams and allows for continuous learning along the way.
In short, transforming an IT department is not just about structure or hiring it’s a holistic change that touches structure, culture, and how the whole organization operates.
The importance of culture and management
Ismaïl : You place a strong emphasis on culture, values, and the human side of things. How important is management in your role as CIO ? And have you trained on these topics ?
Sebastien : That’s a great question. In my view, there’s first a part that’s innate : linked to personality. I’ve always been more drawn to the “big picture” and teamwork than to pure technical expertise. What I really enjoy is keeping a global vision and helping the team grow, not diving 100% into the technical side.
Then, it’s something you learn and develop. I’ve had the chance to work with extraordinary leaders, and I’ve learned a lot by observing how they operate. I read constantly : books, articles, I watch videos, attend conferences… anything that can help me reflect on leadership and management.
I also like the analogy with sports: the CIO is like a team coach. They need to identify talent, manage fatigue, place the right profiles in the right roles (back office, front office), etc. That approach fits perfectly with the corporate world, and I find it incredibly inspiring.
Assessing IT Department Maturity
Ismaïl : How do you assess the maturity of an IT department before deciding to transform it ?
Sebastien : It’s a complex question, and I don’t have a one-size-fits-all answer. That said, there are a few approaches I tend to favor:
- Interviews & Listening : I start by meeting with the IT teams, but also with business teams (business partners, AMOAs, Product Owners) to understand their pain points and expectations. These field insights are extremely valuable.
- Vision & Strategy : I also engage with top management and COMEX members to understand their strategic priorities and ambitions. Having that level of input helps filter and prioritize IT topics in alignment with the company’s overall strategy.
- Shared Diagnosis : By combining both sets of insights (from the field and from leadership) you get a clearer view: what are the main pain points, the urgent needs, the growth challenges? That’s where the “maturity” of the IT department starts to emerge, particularly around areas like data, infrastructure, or governance.
In short, assessing maturity means first listening to all stakeholders to understand their perspectives and needs, and then building a shared diagnosis to guide transformation priorities.
The ratio of IT directors to the number of employees
Ismaïl : Do you have a standard ratio between the number of IT staff and the total number of employees in the company ?
Sebastien : Not really. You’ll find benchmarks suggesting around 3 to 4% of the total workforce (including both IT headcount and budget), but that largely depends on how you define the scope of the IT department.
- At Doctolib, for example, there was a team of 700 people managing the platform but that wasn’t the IT department, it was part of the “product tech” organization.
- At Altavia, we also have technical teams building solutions for our clients, but they aren’t part of the traditional IT department either.
So, it really depends on the company’s business and structure. If you stick strictly to the IT department’s core functions, a 3–4% ratio can be a general reference, but it varies widely.
Internal vs. external ratio
Ismaïl : And do you manage the ratio between internal and external resources?
Sebastien : It’s always a balance that needs to be adjusted based on the situation. When I joined Altavia, the internal team was small, there weren’t enough available skills, and we had major projects on the table (SAP, CRM, and so on). So we made the decision to scale up to 70% external resources in order to move quickly with senior, experienced profiles.
I presented this strategy to upper management to explain the need to temporarily increase the “external services” budget. They approved it because it was part of a broader plan: the goal was to quickly launch these critical projects, then gradually bring the expertise back in-house to build long-term knowledge and stability.
The IT department is not just the CIO...
Ismaïl : The IT department isn’t just about the CIO… Who do you rely on to lead the transformation ?
Sebastien : As CIO, you can’t carry every message or be behind every team member all the time. In the beginning, it’s important to lay the groundwork yourself, to establish governance and methodology. But very quickly, you need to delegate to an internal team.
In my last two experiences, I’ve taken two different approaches :
- At Doctolib, I had a small team focused on IT strategy and major project management. We informally called it the “CIO Office.” They handled the roadmap, rituals, reporting, and so on.
- At Altavia, I rely more on the architecture team, which also has a strong project culture and is capable of driving cross-functional governance.
Regardless of the title (architecture, PMO, etc.) what matters is having someone who enjoys and excels at project management, team coordination, and methodological oversight. That person becomes the linchpin of the transformation, ensuring both coherence and continuity across the board.
The CIO's business "drive"
Ismaïl : I understand that you have a strong business-driven mindset in your vision of the IT department. You place a lot of emphasis on alignment with the business, but sometimes disruption can come from technology itself (like AI). How do you approach these disruptions?
Sebastien : Today, a CIO can no longer afford to stick to a purely technological approach. We don’t do IT for the sake of IT ; we do IT to create value for the business and support its strategy. That means listening to business teams, understanding their needs, and putting technology at the service of real-world challenges, all while staying one step ahead of what can boost performance or competitiveness.
The resources available (budget, teams, service providers) are just means to an end. The focus must remain on the business value delivered. In that sense, technology becomes a lever for acceleration. Within this framework, it’s essential to have solid, consistent foundations, whether it’s cloud, security, digital workplace, or work methods, so that innovation can be layered on without undermining the whole structure.
The question of technological disruption (like AI) fits naturally into this dynamic. We can’t ignore these shifts, as they can provide significant competitive advantages. At the same time, we need a clear strategy and well-defined “rules of the game” to integrate these new building blocks coherently. For example, if we choose to move to the cloud, it’s critical to embrace automation and on-demand consumption, not just do a “lift-and-shift” that amounts to relocating servers as-is.
We must also not lose sight of the trade-off between modernizing core foundations and delivering quick-win, business-oriented projects. It’s about finding the right balance: modernizing the technical stack (so it doesn’t become a bottleneck later), while continuing to deliver features and solutions that address immediate business needs. This way, the business quickly sees the tangible value of IT, which strengthens trust in the broader transformation.
Finally, to keep this vision consistent, I rely heavily on a solid enterprise architecture. That’s what formalizes the overall logic : which components to adopt, how to make them interact, which standards to follow, and so on. Without that architectural backbone, there’s a risk of fragmentation, multiplying technologies or conflicting approaches, which in the end complicates transformation and slows down innovation. Architecture acts as the glue between business vision and operational reality, and that’s especially critical when introducing disruptive technologies like AI or any other major innovation lever.
Support : still the backbone of IT?
Ismaïl : We’re talking about transformation, AI, business… but what about support? Is it still the backbone of the IT department?
Sebastien : Absolutely. Many IT departments get so absorbed by strategic projects (AI implementation, ERP overhauls, and so on) that they sometimes forget about the day-to-day user experience. And yet, that’s often the first thing employees notice. If the Wi-Fi doesn’t work in a meeting room, or if a video call drops mid-conversation, the IT department’s image takes a hit instantly.
I like what a former manager once said: these things should “make zero noise.” They should just work. It’s like starting your car in the morning: if it’s reliable and functional, you don’t even think about it. In the same way, quality support is a basic expectation in every company, big or small.
To give you some metrics : at Doctolib, we invested heavily in this area because employee experience and the ability to attract and retain top talent were absolutely critical. We had a very high ratio: one full-time support person for every 150 employees, which is extremely high-quality. The investment made sense, because even a small dip in productivity could have a big impact on the company’s momentum and growth.
Personally, I always keep an eye on the ratio between total staff and dedicated support roles. It’s a key indicator to avoid getting overwhelmed by headcount growth and to maintain a flawless level of service. After all, if the IT department wants to be credible in driving major transformation, it first needs to excel at the basics.
