Some business systems can serve you reliably for years. Others start holding the company back fairly soon after they go live. How can you tell if you have a legacy system on your hands?
A legacy system is any system that holds a company back instead of serving it, regardless of its age.
You might think legacy systems are programs written in COBOL or Delphi. But whether a system is outdated isn’t determined by how old it is. What matters is whether it still serves the company or is starting to hold it back.
A well-maintained information system written at the turn of the millennium can still be working fine in 2026, with excellent security, support and documentation. On the other hand, an app that’s just a few years old, or a tool built with AI, can become legacy too.
You can even create a legacy system yourself. All it takes is customizing an off-the-shelf solution to fit your established but poorly designed processes. Every time the vendor releases an update, you have to check whether your customizations still work.
Your system is legacy if at least one of the following signs applies to it. The more of them you recognize, the higher the risk.
One of the tricky things about legacy systems is that it may not be obvious at first glance how they’re holding the company back. Everything might seem to work: you pay for system management and updates, you enter data… The problem usually surfaces when something changes: you want to launch a new product, people leave, or you merge with another company.
A legacy system can limit your company’s growth, because every new feature is slow and expensive to build. Our clients typically find themselves in one of two situations:
In both cases, the problem tends to be poor support from the software vendor or difficult scaling. If your competitors are happily rolling out new features while you wait weeks for a button color change, your software is becoming a drag on your business instead of supporting it.
The worst-case scenario is a complete system outage: production grinds to a halt or customer orders get lost. But losses in everyday operations are more common, and just as costly.
Imagine a key client comes to you with an order that will secure your cash flow for several months. But your system can’t handle the type of contract or the pricing the client needs. Modifying the system would take weeks, and onboarding even longer. The client won’t wait that long, and you don’t want to lose the business, so you go to a colleague who edits the data manually, straight in the database.
If it happens once, you might turn a blind eye. But what if your colleague has to go into the database every day? Then you’re paying a person to do work the system should be doing. You’re wasting human talent and risking errors in your data. That’s why we recommend looking closely at how your critical systems affect operations, not just in unexpected situations like an outage, but in the company’s day-to-day life as well.
The short answer: because it can’t be patched. If the vendor has stopped releasing security patches, or the system runs on an unsupported version of an operating system or database, every newly discovered vulnerability stays open for good.
In older systems, these are the weaknesses we see most often:
And then there’s regulation. The new Czech Cybersecurity Act, which transposes the EU’s NIS2 directive into Czech law, extends obligations to thousands more companies, including risk management and supplier management. Personal data falls under GDPR, and the financial sector is also governed by the DORA regulation. A system that can’t handle basic security measures exposes a company not only to attacks, but also to regulatory non-compliance.
What is the bus factor and why does it matter?
The bus factor is the smallest number of people a piece of software depends on. It’s a frequently overlooked problem with legacy systems, and in many cases, that number is just one. When that employee leaves or falls ill, the system keeps running, but you have no way to fix it or develop it further.
That’s why we recommend making sure you have more than one person at the company who knows the system and understands:
It’s time to modernize when the system starts limiting the decisions the company needs to make. With our clients, we most often see this in the following situations: