Legacy system modernization has become one of the most pressing challenges today. Technical debt keeps growing and every update requires more effort than it should. At a certain point, you realize that your old system limits business growth.
Modernization doesn’t have to mean a radical rewrite. When done right, it is an evolution, not a revolution. To explore what that process should look like, we talked with Mateusz Cieślak, CCO at People More.
See how one of our Clients went through legacy modernization, without shutting down operations or disrupting customers.
Why is legacy system modernization becoming so urgent for companies? Many still try to postpone it.
Because the environment around them has changed dramatically. Systems built a decade ago were never designed for the level of connectivity and cloud adoption that modern business requires. Today, companies want fast delivery, seamless integrations, clean data flows and the ability to experiment. Legacy systems struggle to support all this.
The important thing is that modernization isn’t about wiping the slate clean. It’s about taking a system that still carries business value and redesigning it so it can continue to evolve. The best modernization strategies show exactly how to modernize legacy systems without downtime. You create new components alongside the existing system, gradually shifting traffic and functionality as the modern architecture takes shape.
Before modernization begins, what should companies assess? Where do the real blockers usually hide?
Most organizations assume the code is the biggest issue. However, the issue is usually architecture, integrations or the data layer. When the architecture is too rigid, every change becomes complicated. When integrations are built on outdated ESB models, even the smallest extension requires navigating a maze. And no amount of code optimization will solve the problems with the database that became a bottleneck.
This is why the first step in a legacy software modernization project is a proper consultative analysis. You need clarity on what is holding the system back and which parts have the biggest business impact.
And how does the modernization process unfold once the blockers are identified?
Modernization should always happen in parallel. You don’t shut the system down, you build the new one next to it. The process typically begins with backend and architectural improvements, because that’s what determines delivery speed in the long run. When that foundation is in place, the next step is to modernize the integration layer, redesign the APIs and introduce communication patterns that allow the old and new components to work together.
Only after the integration layer is stabilized does it make sense to modernize the data layer. This is where companies often worry about downtime, but there are mature techniques such as shadow tables or dual-writing capture that allow data migration to happen gradually and safely.
UX and UI changes come last, when the system is already stable, fast and better aligned with the organization’s current needs.
This sequence reflects what we see in successful modernization efforts across industries and we do it accordingly at People More.
So, basically you start with the fundamentals, then move upward. But what about risks? Modernization is often seen as expensive and more complex.
The biggest risk is actually doing nothing. But the second biggest is trying to modernize everything at once. Legacy software modernization becomes safe when it’s planned as a continuous process rather than a one-off project. Companies need to decide what brings the highest value with the lowest operational risk and modernize in that order. One organization might gain the most by replacing its integration layer; another might need to restructure the database first. There’s no universal starting point. The key is prioritization and a clear roadmap.
If a company wants to start this journey, what would be your first recommendation?
Start with a conversation, really. Not with technology. Understand what is slowing the business down and where the system struggles to keep up. Only then you can design a modernization path that makes sense. Legacy system modernization succeeds when the company knows exactly what it wants to achieve and chooses the right sequence of changes.
Once that clarity is in place, the process becomes much less intimidating. And if someone needs help understanding where the best starting point is, we’re always ready to support them.
Thanks for the conversation!
You’ve read a conversation with Mateusz Cieślak.
Ready to modernize your legacy system? Let’s build your modernization roadmap together.
Tomasz Michalik
