Legacy system migration.

We live in the era of skyrocketing technologies, AI, cloud-based solutions, and Metaverse. So both small businesses and enterprises do their best to stick to the latest tech trends and stay up-to-date for the sake of competitiveness… Right?

Now, here is what statistics say. More than 30% of organizations still run systems built more than twenty years ago. Can you believe it? Well, outdated software is much more common than you might think. Many companies don’t rush to abandon their old familiar legacy systems. They prefer to maintain the existing solution because modernization or complete replacement seems too complex and risky according to legacy software trends.

Nevertheless, most businesses start to think about at least partial modernization sooner or later. And if you choose the right approach that corresponds to your goals, this upgrade will certainly be beneficial.

But how to make the right decision and ensure successful legacy system modernization? This article will help you clear things up.

We will rely on Acropolium’s rich experience in transforming legacy software to explain the following:

  • A legacy system definition and reasons for updating it.
  • The possible approaches to partial and complete modernization.
  • The reasons for maintaining a legacy application instead of modernizing it.
  • The critical challenges of legacy system migration.

What Software Can Be Considered a Legacy System?

A legacy system is an outdated software or application based on obsolete technologies that are still in use for some reason. Such a system was designed years (or even decades) ago, making it difficult to operate, support, and maintain.

According to the Gartner definition, legacy software is one of the most critical challenges for modern IT professionals. It’s because tech specialists should struggle to find ways to bring outdated formats into line with new standards. The main obstacle is the integration of new processes and systems into the existing legacy software.

Several key indicators help define a legacy system and distinguish it from other types of software. And although the app’s age is critical, many other factors also matter.

In particular, legacy systems require modernization for the following reasons:

1. Legacy systems tend to be insecure.

2. Outdated software is challenging and costly to maintain and support.

3. Integrating with a legacy system is difficult or impossible.

4. Non-modernized systems often face compliance challenges.

5. Legacy software might become a burden preventing your business from growing.

Legacy System Examples

Remember the statistics we mentioned at the beginning of the article? According to a detailed Avanade report, more than 30% of modern businesses still run outdated technologies. Meanwhile, the percentage of companies that have upgraded their systems is almost the same.

Breakdown of organization's technologies

Legacy systems are prevalent in the industries and segments that run outdated technologies and applications built years ago. For example, this may be the case for federal organizations, banking, retail, healthcare, etc. Very often, they cannot modernize software due to the importance of operating it without interruptions.

At the same time, It puts at risk many vital processes and may result in critical crushes. For example, in 2017, a computer failure at the Internal Revenue Service led to a complete stop of electronic tax return delivery for millions of Americans.

Should You Keep or Replace a Legacy System?

To modernize or not to modernize, that is the question.

Many companies and organizations prefer to keep their legacy systems because changing them for new ones is painful. The others, in contrast, are ready to go for a partial migration not to lose most benefits of the existing software. And finally, some choose the most radical approach: complete modernization.

Gartner offers a more detailed classification of legacy software modernization techniques. We have grouped similar approaches into three main types for your convenience. Besides, we will briefly describe each of them and explain the specifics of these solutions.

So, let’s look at the possible approaches to help you find the correct option for your individual needs.

Software modernization approaches.

When Is a Full Legacy System Modernization Needed?

It’s worth mentioning that a complete legacy application modernization is not always necessary. Many companies opt for solutions that require less time, cost, and resource investments. However, there are no other ways out in particular cases but complete migration.

Most often, a complete software modernization is rather an abandonment of the old system and the launch of a new one from scratch.

This approach is suitable in the following cases:

  • Your software is critically outdated and almost impossible to maintain.
  • Your system has crashed and is not fully recoverable.
  • Your business goals have changed, and no legacy application components now meet your current needs.

However, many consider this approach risky and too complicated for the following reasons:

Keeping the above in mind, let’s consider the two most common options of complete legacy modernization.

Software migration process.


This technique involves the development of a new custom solution tailored to your current business needs. The engineering team will rewrite the code, change functionality, and interface design, and replace outdated technologies with modern ones. In other words, you will get a completely new application developed from scratch.

This solution perfectly fits those who decided to move to a more convenient, up-to-date environment. However, it allows keeping the business logic of the previous system. Thus, it won’t be difficult for your employees to adapt to the new software.


Unlike the rebuilding approach, replacing is about a complete upgrade of all software aspects which include the structure and business logic. Therefore, you will get a completely different solution with its scope, structure, and system components.

Replacing will be suitable for those whose legacy system doesn’t perform its tasks anymore. Thus, they need a new environment corresponding to the changed requirements.

When Is a Partial Legacy System Modernization Needed?

A complete rebuild or replacement of your legacy system may be risky, challenging for your team, costly, and time-consuming. So in most cases, when the required changes are not that significant, organizations and businesses opt for partial modernization.

This section will discuss multiple approaches and techniques for incomplete legacy system migration.

The goals of those choosing such solutions differ as well. However, all these approaches reflect one thing – the desire to preserve particular aspects of the existing system and, at the same time, improve its performance.

Here are the most common reasons for turning to partial modernization.

  • Your legacy system performs its tasks well, yet certain aspects require improvements.
  • You want to overcome the obsolescence challenge and integrate newer technologies.
  • Your security system has become vulnerable.
  • Your software architecture doesn’t allow for scaling.

At the same time, the following factors may prevent you from turning to partial modernization:

  • Sometimes it’s harder and more time-consuming to modernize a legacy application than build a new one from scratch.
  • If your legacy code is outdated and lacks documentation, developers may find it challenging to improve it.

Now, let’s look at different approaches to partial modernization in more detail.

Data migration process.


Encapsulation is one of the most cost- and time-effective legacy system modernization strategies. The changes apply only to the interface that connects to the existing legacy system via API. Therefore, the code, architecture, and other key system components will remain the same.

This technique may perfectly match those looking for design and functionality improvements. Additionally, it will allow you to significantly reduce development time and cost. However, you will still have to maintain the existing solution. Thus, if your legacy code is outdated and software lacks reliability, it’s worth considering other modernization approaches.


When rehosting your legacy systems, you transfer them to a new environment without any critical changes to the application itself. It resembles moving to a new, more secure house while keeping all your belongings. With this approach, you won’t have to spend much time and effort as the migration process is relatively straightforward and seamless.

You can rehost your legacy system in two ways:

The latter one, in particular, is an excellent option for those who want to scale their systems, enhance capacity, and migrate to a more secure database.


When re-platforming your legacy software, you move its components to a new platform without changing the code much. This approach is suitable for those who strive to avoid common modernization challenges. In particular, re-platforming will allow your employees to avoid struggling to learn a new system. Most of its former components will remain unchangeable.

Replatforming also enables you to benefit from certain cloud infrastructure features, including reduced maintenance costs. However, due to partial migration, many native cloud capabilities won’t be available.


Most legacy applications are based on monolithic architecture. It means that the system’s components are strongly connected. Thus, it’s much harder to boost scalability and software performance. In turn, when rearchitecting your system to a microservices structure, you will get a more flexible solution to grow.

The goal is to rebuild your system based on a new, more scalable architecture. It allows businesses to expand functionality, improve security, and integrate modern technologies.

This legacy modernization approach is perhaps the most complex and challenging among partial system updates. It requires a significant effort from your development team. On top of that, changes in business logic are inevitable.


This modernization approach is also called re-coding. It involves changing your system’s legacy code without transforming the entire environment. Refactoring is reminiscent of a repair inside your house instead of moving to a new one.

The implemented changes will affect the system’s functionality and configuration. Thus, you can improve maintenance efficiency without extraordinary modifications. This solution will perfectly fit an organization or enterprise generally satisfied with its legacy software but sometimes suffering from tech issues.

When Is It Best to Maintain Legacy System

Despite all advantages of IT legacy modernization mentioned above, many businesses still prefer to maintain the existing software. And in many cases, this decision makes sense.

Let’s look at situations where updating your legacy application may be inappropriate or unnecessary.

Support and maintenance process.

Your Legacy System is Efficient

The most widespread argument for maintaining the existing solution is its ability to perform the required tasks and meet current business goals. But how can outdated software handle today’s challenges? Well, that’s more likely than you may think. Most legacy systems are more or less stable and reliable.

Moreover, the tech team responsible for support and maintenance is often so accustomed to good old technologies that replacing them brings more stress than satisfaction.

Thus, one shouldn’t replace legacy IT systems just because they are outdated. Instead, it’s worth considering modernization when they truly lack efficiency or no longer meet your business goals.

You Cannot Interrupt Your Business Processes

Another good reason to keep maintaining your legacy software is a vital necessity of operating it without interruption. It’s a common motivation for medical, financial, and federal organizations to continue using the existing solutions.

Some complex updates may take months or even years. So if the existing solution is stable and you cannot pause the business processes, maintenance is often less risky than modernization.

Issues with Migrating Legacy Systems

As you see, legacy system replacement is not always a cakewalk. More often, it’s a complex task that may result in potential risks for your business.

Here’s all you should know about legacy software modernization challenges.

  • Lack of planning. Many issues may occur during the legacy system transformation process because of the wrong strategy and lack of analytics. So when making critical decisions, it’s a good idea to involve engineering, compliance, and security specialists. It will help you save time, money, and effort in the future.

  • Data management. Many hesitate to modernize their systems because of data loss risks. However, it’s also essential to pay attention to the cleanliness and relevance of the data you migrate. Don’t transfer old inaccuracies to the new environment.

  • Completely new technologies. With the existing system’s complete or partial replacement, your company’s employees will have to adapt to operate new software. Learning how to handle it will take time and effort. So try to choose the technologies that won’t be too difficult to cope with.

  • Time and resource investments. And finally, such a complex and multilevel task as IT legacy modernization will require significant time and resource investments. Of course, to evaluate the exact price and timeline, you should consider your project’s scope and other specifics. Also, you will have to find a reliable tech partner with relevant experience and a meticulous approach to the migration process.

Digital transformation pitfalls.

Our Experience

We at Acropolium have rich expertise in legacy software modernization. We’ve come up with more than fifty efficient optimization solutions and have ten years of experience working with digital transformations.

Hopefully, the following case studies will help you better understand outdated systems’ improvement processes and gain valuable insights.

Complete Offline to Online Transformation

Working on this project, we had to conduct a full-fledged digitalization of an offline document system and automate numerous business processes.

Our client was an international trade software provider focused on export/import procedures and documentation. They needed a robust SaaS solution to move from paper-based manual work to an efficient digital environment. Besides, the app was supposed to verify international shipping requirements.

Thus, our primary goal was to build a system providing automated documentation, shipping requirements checks, and secure data storage.

Here are a few challenges we had to handle:

  • Moving offline business processes to a digital system.
  • Automating the storage for order and shipping data.
  • Solving the domain and documentation issues.

First, we came out with a solution allowing for the output of PDF formats. Also, we found a way to generate the documents in compliance with governmental regulations. Next, we added multiple additional features:

  • A convenient interface for data storage.
  • Solutions for storing customs documents and declaration submissions via API.
  • Efficient functionality for user and company management, subscription plans, internal chats, notifications, etc.

As a result, our client got a 37% increase in new enterprise customers. In addition, the cost dropped by 60%. Finally, we completely digitalized the client’s business and automated all filling declaration forms.

Optimization of a Shipping Service Platform

A shipping service provider asked us to build an MVP of a mobile app and optimize their existing web platform. The solution had to allow tracking of the drivers’ working hours and providing payments for particular periods.

Our team’s key goal in this project was to address the driver overtracking issue and guarantee timely payments. Also, we had to build an MVP of a mobile app and meet fairly tight deadlines.

Our tech specialist carefully investigated the existing solutions. We found a few critical issues during the audit phase. They could negatively affect the app’s scaling, maintenance, user experience, and security. To solve these problems, we optimized the architecture, fixed them, and, most importantly, optimized the code.

Finally, we improved an Android mobile app and built an iOS app from scratch. Our company completed all these tasks in just three months.

As a result, the system’s security level increased by 90%, and the session speed grew by almost 30%.

Choose Your Tech Partner for Painless Legacy System Modernization

Every technology, application, and the digital system has its lifespan. And sooner or later, it comes to an end. It is essential not to miss the right moment and upgrade your legacy software before it ceases to serve your business effectively.

However, a one-size-fits-all solution doesn’t exist. Some prefer to rebuild the entire system. Others gain more benefits from partial code rewrite or cloud migration. It all depends on your individual case.

That’s why we always recommend our clients start with careful planning. Before optimizing your software, consider numerous factors like your business goals and potential future risks. Comprehensive analytics and a well-established strategy are the best practices for choosing the legacy system modernization approach corresponding to your needs.

Therefore, if you are looking for a reliable partner to improve, migrate, or replace your legacy software, we at Acropolium are ready to help.

We are experts in digital transformations. Our team has dealt with numerous complex IT solutions serving various industries. In particular, we perform top-notch legacy system modernization. Our experts are ready to conduct in-depth software and architecture audits. We will consult you on modernization approaches depending on your objectives and make every effort to help you find the right solution. Here are the optimization services we often provide:

  • Complete modernization
  • Third-party integrations
  • Code refactoring
  • Platform migration
  • Performance assessment

Drop us a line, share your idea, and we will find the right way to modernize your software.