Guide to legacy system modernization approaches

Legacy system modernization is quite a puzzling umbrella term, covering a whole range of activities and techniques. It may actually sound intimidating for many people – after all, it usually involves a lot of time, financial resources, and effort to implement complex updates. 

What’s interesting, however, is that postponing the process is often more risky and disturbing for the company. The firm’s expansion, market dynamics, and the global technology shift force you, in some way, to modernize the system your business relies on. Introducing the changes smoothly while also keeping the risk at a minimal level is not an easy job. It is possible only if you go for a suitable legacy system modernization approach. Which path to choose to see your company bloom? Let’s check out the options. 

What should a legacy system mean to you?

Before diving deeper into different legacy system modernization approaches, let’s first take a step back and focus on the software that actually needs it. It is commonly known as a legacy system, but what does the term really mean?

In fact, there is no one-size-fits-all definition that we could apply here. Everything will depend on a specific business and its characteristics. Contrary to popular belief, the age of the software is not always crucial because a legacy system might still be relatively young. Of course, often, the timeline does matter. The thing is, it’s not the rule. If not age, which red flags should you look out for, then? 

You may notice, for example, that the system doesn’t serve the company’s needs anymore or doesn’t keep up with business-related changes. It is also considered outdated or non-performant when juxtaposed with the modern technologies overflowing the IT landscape and gaining fans across different sectors, like AI algorithms or big data. Finally, the application could have been created without programming standards in mind and with a very close-minded attitude, which is currently stopping the company’s growth. 

In short, a legacy system is any kind of software jeopardizing daily business operations. 

The problem is that this system usually plays a critical role in the company activities, and it’s difficult to introduce any changes without disturbing the daily workflow.

The problem with legacy applications

Keeping in mind how demanding the modernization process might be, why bother in the first place? The answer is quite simple: keeping an outdated, inefficient system isn’t good for your company either, especially in the broader perspective. Legacy applications tend to generate challenges and problems in different areas, both technical and operational, all of them taking a toll on your business.

Increasing costs

It may seem that undertaking modernization efforts will involve a lot of costs. While it is true in the short term, adopting a relevant legacy system modernization approach certainly brings more value and savings in the long run. It turns out that keeping the outdated system is, in fact, more expensive. It’s related mainly to maintenance cost and working your way around processes you cannot automate because your software doesn’t allow you to. Apart from that, the outdated system prevents you from entering lucrative opportunities while your competitors are thriving. 

Decreasing security

Financial challenges are not the only issue, though. Legacy code means the solution is prone to both internal and external threats, malware, or other security breaches. Outdated security protocols and algorithms that don’t go hand in hand with modern standards put your credibility and reputation at significant risk. It is considered good practice to stay up to speed with what’s going on in the tech world and make sure your software reflects those changes. It means you can easily integrate with the most innovative, future-proof solutions, ensuring that your system is safe to use.

Compliance issues

Neglecting security standards and modern processes may also lead to serious compliance problems and wreak havoc in the whole organization. More and more regulations need to be followed, especially in the industries processing vast sets of sensitive information, such as finances and healthcare. If the company’s activities don’t align with the local and central law, one can face severe consequences and gigantic monetary penalties. And it’s not easy to monitor the situation and keep track of compliance rules having an outdated and chaotic system.

Losing competitive advantage and hampering growth

Not only does holding on to an outdated system carry a risk of losing data or receiving a fine. The consequences might also be much more practical, related strictly to business growth, or rather a lack thereof. While the competitors take an active part in the innovation race, trying to address the current market needs, the company relying on legacy software is left behind, losing competitive advantage and slowing down the progress. If changes and improvements can’t be implemented smoothly, you’re stuck in a very vulnerable position from the business perspective. Should this state be prolonged, the company might not be profitable anymore. 


Killing productivity

Finally, using a legacy system also takes its toll on regular employees and their productivity. Everyday processes take much longer to accomplish, daily operations are disturbed, and a workflow structure is non-existent. Weak software performance is more of a burden than a help for the company. All these factors make the work ineffective and the staff unmotivated.

Before you pick the legacy system modernization approach

Okay, you’ve got a grasp of the risks related to using a legacy system. Based on this information, you decide to go aboard the modernization journey and make the first big step towards a change. 

Before you choose the right approach, though, it’s worth having deep thought about your current status and future plans. Only then, you’re able to make an educated decision regarding the modernization path. 

At this initial stage, it’s vital to perform thorough research and planning (with the help of experienced tech specialists) to define clear goals and priorities. Try focusing on what’s bothering you the most, what’s the most time-sensitive, and what will bring the most value to your business. This step will enable you to go for the optimal, solution-based approach.

  • Assessing the current stage of your software 

Assessing the current stage of your software is always a good starting point. To make it the most efficient, try to engage tech experts knowledgeable about your business area. They will perform a set of activities to confirm where you’re at and where you need to be. These may involve a comprehensive solution and market analysis, a code review, or a workshop session to discover the pain points and areas for improvement. At this point, it’s worth using metrics to gain a clear picture of the situation and decide how to implement changes.

  • Identifying the problems and defining goals

This is the essential step in embarking on the software modernization journey. By asking questions and examining different system elements, such as performance or user experience, you’re able to point out the main improvement areas. This is a perfect starting point for creating a well-thought modernization strategy and setting measurable, realistic goals for the upcoming weeks, months, or even years. 

  • Analyzing legacy system modernization approaches and choosing the best one

Once you’ve analyzed where you’re at and where you want to be, it’s time to look at the modernization options. You can take a couple of paths, depending on your needs, limitations, and goals. Each of them serves a different purpose, so it’s important to compare them before making the final decision. 

Legacy system modernization approaches

The choice of a relevant modernization approach needs to be careful. To give you at least a preliminary insight into the topic, we’ve prepared an overview of three different paths to take.

Three legacy system modernization approaches

Lift and Shift

The least invasive approach you might consider is the Lift and Shift option. It involves moving a part of your system from on-premise infrastructure to the cloud and requires little to no code modification. This strategy can be applied to enable a fast and smooth cloud adoption in itself and may be treated as the first phase of a more far-reaching modernization endeavor. 

The main advantage of this approach is minimal disruption to your ongoing operations. The whole process is relatively quick and easy to implement (making it also less expensive) and constitutes a great foundation for gradual changes in the future. However, it won’t be a good choice if your system’s architecture has many flaws since the code is pretty much left unaffected in this legacy system modernization approach. 

The Lift and Shift approach will work best if you want to start slow and divide the modernization process into smaller steps. The crucial thing is that your current software needs to be in a workable state and shouldn’t require substantial code/architecture changes just yet. 

Augment and Refactor

Another, a little bit more comprehensive legacy system modernization approach is the Augment and Refactor path. This one addresses software needs of higher complexity, where the code needs to be changed to reach the upgrade’s goals. A refactor may be a suitable option if you cannot develop the system further, e.g., due to outdated libraries, incomplete documentation, weak unit tests, or performance issues. 

Going for this approach is best when your system needs additional features, a performance boost, and substantial changes to code necessary for cloud adoption. It can also be applied as an intermediary stage preceding a profound Complete Rewrite. 

It brings a lot of profit for the company: you gain stability and flexibility ensured by cloud solutions while also reducing the maintenance cost. Bear in mind, however, that the process is longer than the Lift and Shift approach since it involves major code modifications. Moreover, it doesn’t involve the change of your apps architecture just yet.

The Augment and Refactor legacy system modernization approach will be a perfect fit for you if your software needs to keep up with the business growth and you plan on adding new features. 

📙 Case study of Augment and Refactor modernization for SafeEx

This is exactly what worked for SafeEx, a Danish company that wanted to sharpen its inspection & maintenance tool for the oil and gas industry. Since their tool has been in operation for over a decade, the client needed to ensure it’s still capable of keeping up with the organization’s business growth. Among the solutions we proposed to improve the application’s performance, there was a code refactor, migration to PostgreSQL and AWS, switch to Python 3, and Mobile App Push Synchronization API revamp. The result was up to 10 x performance boost of individual views within the system.

SafeEx system screenshot

Complete Rewrite

Last but not least, there is a Complete Rewrite strategy, the most wide-spanning and benefits-packet legacy system modernization approach. It’s a perfect choice if the business circumstances in your company have drastically changed and a small modification would not be sufficient anymore. 

Rewriting the system provides you with a substantial update and a fully personalized solution, which is based on a future-proof architecture and design. Going this path enables you to start fresh with the best standards and practices in mind. Obviously, far-reaching changes require more time and financial investment. They will also have a noticeable impact on daily company operations, which is why it’s crucial to implement updates mindfully. 

You should consider going for the Complete Rewrite approach if your system is so old and outdated that it’s easier (and cheaper) to start anew rather than to maintain it. 

📙 Case study of Complete Rewrite for a business insurance app

This is what we did for a US-based insurance agency. The client found their previous system complicated, unintuitive, and based on outdated technologies. All of that called for introducing substantial changes to the system and switching to a modern tech stack. Our scope of work included revising the way business processes are reflected within the system, choosing up-to-date and scalable tech stack, and rewiring the app accordingly. As a result, the client gained more room for new growth opportunities.


The software modernization approaches vary and may bring different results. It’s important to adjust the plan to your unique case and make the results work for your business. Whichever route you finally choose, make sure to engage an experienced, reliable tech team in the process. This way, you increase your chances for modernization success. 

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