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Legacy System Modernization Approaches: Practical Advice on Dealing with Outdated Software

The world is advancing quickly and what was once a perfect solution, quickly becomes outdated and useless. Have you already made the decision to modernize your legacy system but not sure how to approach this and how to avoid possible pitfalls? Then, this article is for you, as we are going to discuss the most effective legacy software modernization approaches, their benefits, and pitfalls. 

We are going to go through the definition of legacy system modernization and the benefits it can bring. We will also highlight the struggles that legacy system modernization can cause, what approach you should take to overcome them, and the implications of legacy software system modernization. 

What is Legacy System Modernization?

Legacy system modernization is a process of updating legacy software porting it to a modern programming language, software libraries, or protocols, because the use of an outdated technology may result in unnecessary risks.  

So why do businesses need legacy system modernization? First of all, legacy software requires a significant investment of resources for its maintenance.  

Secondly, finding qualified professionals to support the system is a hard task, as not many programmers these days work with outdated languages such as COBOL or FORTRAN.  

Thirdly, outdated software is hard to integrate with new systems due to its architecture, underlying technology, or design, and there’s the risk that it can crash at any time.  

So, if business goals have changed over time, the inflexibility of legacy software could make the implementation of any changes almost impossible, which becomes a significant barrier to business development and revenue growth. 

If the disadvantages of using outdated systems are so obvious, why do so many companies still rely on them and postpone modernization? Many companies use legacy applications for core business operations such as high-volume data processing or conducting day-to-day operations that are essential for the functionality of your organization. Changing some elements of these systems is a risky step as it can bring the whole business to a halt.  

The legacy software is very expensive to maintain, and companies that postpone legacy code modernization will eventually incur heavy technical debt. So, although modernization requires decent investments, any business that wants to stay competitive needs to consider starting the process as soon as possible. 

Why is it a good idea to move the legacy system to the new version? | ModLogix

Why Do You Need Legacy System Modernization?

In order to better understand whether a business needs modernization of their legacy system, it’s important to know the old system’s negative influence on a company’s growth. So, let’s discuss the most common reasons for starting a modernization process now! 

Legacy Software Requires Big Investments for Its Maintenance 

It’s a known fact that legacy systems require an immense budget and is a lot of effort to maintain, therefore modernization is a necessity. For example, the Government Accountability Office public report has revealed that about $337 million is being spent on the maintenance of the federal government’s 10 legacy systems annually. Due to the large codebase and complicated functionality of the legacy software, updating or changing something within the system requires more financial and time resources than modern software. Moreover, legacy systems often require hardware that is also not cheap.

Shortage of Professionals That Can Support Legacy Systems 

After all, you may not find professionals at the right time — legacy systems require specific skills and expertise. Young developers are focused on new technology while most of the COBOL developers who’ve been working on the legacy systems are retiring. So, finding people with the needed qualification is very hard and expensive.

Legacy Systems Are Very Inflexible 

The inability of legacy systems to adapt to modern business requirements significantly slows down business growth. Companies lose business opportunities and struggle to respond to new challenges while competitors have progressed.  

Connections to third-party tools or services require lots of effort. API vendors are compatible with most programming languages and frameworks, but legacy systems do not belong to this majority as they are very unique. Therefore, one must develop custom APIs that are pricy and need more time for development. 

As mentioned at the beginning of the article, the world is developing fast and there are changes in the market every single day. Only the ones who are quick to respond to the legacy system modernization challenge have an opportunity to stay on track and prosper. 

Legacy Software Is Vulnerable to Cyber-Attacks 

The question of cybersecurity is a delicate one when it comes to legacy systems. They have been there for years and attackers know for sure what harmful programs or malware can destroy it. In 2018 US Computer Emergency Readiness Team (CERT), on behalf of the National Cybersecurity and Communications Integration Center (NCCIC) have released an alert warning about the increased hackers’ interest in legacy Enterprise Resource Planning (ERP) solutions. The outdated ERP systems have gaps that have allowed deeper access into the software’s network. 

WannaCry ransomware attack back in May 2017 has revealed the vulnerability of outdated systems no longer supported by Microsoft. More than 300,000 machines operating on Windows XP, Windows 8, and Server 2003 have been affected in 150 countries because they lacked security updates. What more evidence do you need?

Legacy Systems Don’t Comply with Modern Regulations 

Data protection regulations such as CCPA completely change how we store and use data by requiring more effort on the business side to protect it. Not only the government but users themselves want companies to use their data in a safe way.

Laws such as HIPAA for the healthcare sector and GLBA for the financial one have recently applied some changes concerning the process of using and storing people’s data. So, businesses need to readjust their system in order to adhere to all the regulatory requirements.

Legacy System Modernization Approaches

Since we’ve discussed reasons for legacy modernization, let’s move towards modernization approaches. There are various legacy system modernization approaches that are designed to meet different needs and have unique characteristics. We’ve broken them down for you below. 


Encapsulation is the process of reusing the main components of the system and omitting the legacy code while connecting it to the new access layers via APIs.
This legacy software modernization approach provides a new interface to the old components in order to leverage the app’s functionality; however, encapsulation won’t solve the maintenance issues. So, if you want only to change the interface part, encapsulation would be a great choice that also minimizes costs and reduces risks.


Rehosting ensures easy migration of the whole system to new hardware, cloud, or virtual environment. Although rehosting is generally considered just a step in the app migration process, it helps resolve support issues regarding open systems like SQL-based x86 environment or the cloud.

Due to this approach’s low risks, it’s popular among large enterprises that want to improve the system’s performance while not disturbing its workflow.


Replatforming allows you to migrate components of an application to a new platform with minimal changes in the code. You do not have to change core code or features, which is very attractive to those who do not want to modify “too much” or are worried that users will not be able to use the new system.  

However, little changes mean restricted benefits. You will only be able to adapt to the components that are running on a new system and others will be not able to stay up-to-date for the modern market.


Refactoring is the process of improving the internal component of an old system without changing its external environment. It’s a great choice to make modifications in the configuration, solve tech issues, and make the code more clear and maintainable.

Refactoring makes the system more flexible so it can easily adjust to the current circumstances. This approach is recommended for businesses that want to move from containers to microservices in order to avoid software failures.


This approach is about altering the application code’s architecture to resolve performance and scalability issues. It is a fairly complex process that requires advanced technical skills.

Rearchitecting provides diverse benefits, such as improving app functionality and simplifying the process of integrating new features in the future. However, this approach is quite risky, as it can change the logic of a business and the way the system works in general.


Rebuilding is a huge undertaking, but it is the best custom solution that you can get. Basically, a new system is built from scratch according to the needs of a business. The legacy system components must be rewritten and new functionalities must be built. New coding techniques reduce the time of development, improve security, and create custom network protocols. For example, sometimes you must partially rebuild your system to migrate from .NET Framework to .NET Core, as the legacy components won’t fit the new software.  

The approach is also known to be more high-risk, as it applies a lot of changes to the original system.  

6 legacy system modernization approaches for business | ModLogix

You can learn more about modernization approaches and when each of them can be applied here


What Legacy System Modernization Approach Will Work Best for Your Business? 

As you can see, there are various legacy modernization approaches that you can take. But how to decide which one suits you best? Honestly, there is a lot of decision-making in the modernization process, and it is not always easy.  

In order to decide which approach to modernization of legacy systems is right, you must understand that choosing the most common or popular route is not an option. Every legacy system, and every business, is unique and what works best for one system can be a mistake for another.  

Re-engineering of the Large Management Platform

Re-engineering the healthcare reputation management platform to eliminate unnecessary expenses.

Re-engineering of the Large Management Platform

It’s always better to consult with experts before making such an important decision. You can book a free consultation with the ModLogix team, so we can assess the current state of your system and create your custom modernization strategy.  

Some of the ways to modernize a legacy application | ModLogix

At ModLogix, we know the importance of understanding all the particularities of your business. That is why we have a set of questions that help us make final decisions on which modernization approach would work best for your project.   

  • What technical skills does your organization already have?  
  • How much time do you have for the modernization process?  
  • Do you have complete technical documentation about the changes your legacy system has undergone?  
  • Do you have a platform that you want to move to?  
  • Is your legacy system active or is it on “life support” mode?  
  • Do you plan to update and add integration points often?  

The client’s answers to these questions allow us to have a complete picture of the modernization process and which approach should be applied.

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Our Experience

The goal 

Approved Admissions is a cloud-based eligibility verification platform aiding healthcare workers in validating patients’ eligibility for insurance. The business needed to solve legacy code issues as its software was written 5 years ago, and the company’s rapid growth has revealed the system’s limitations.  

The steps we took 

We decided to move the system from ASP.NET MVC to .NET Core 3.1 to improve the platform’s performance and internal security. We took the following steps during the modernization process:   

  • Resolving technologies disparity issue. 
  • Replacing outdated dynamic site navigation. 
  • Optimization of the software’s code to make it cleaner. 
  • Improving the front-end structure of components.  

Read the full case study revealing the migration process in-depth.

Our achievements 

The system modernization has helped Approved Admissions significantly improve performance, enhance the structure of front-end components, and create a flexible and secure system.

The ModLogix team has also made the system modernization seamless for users, thanks to the special algorithm that didn’t require them to re-login onto the updated system.

Approaches used 

To help Approved Admission modernize its legacy system, the ModLogix team decided to use a combination of two approaches: replatforming and refactoring.  

Why these approaches? 

By replatforming the system and optimizing it to a new environment, we’ve simplified its maintenance, improved the performance, and reduced the per-transaction cost.  

We also wanted to make the software more flexible, so it would successfully serve the business’s needs. To reach this goal, we decided to use refactoring to make the code clearer and more readable.

In most cases, a combination of approaches is used, as it helps the system to perform the operations correctly and saves the company’s resources. Even if the company chooses to use a particular approach during the planning stage and then, while implementing the changes, an additional approach might need to be used. The complexity of software modernization requires professionals to be involved in order for the process to be successful.  

The ModLogix team has years of experience providing legacy system modernization services. Feel free to contact us if you want the modernization process to be conducted the right way, understand how to test legacy code, and bring positive outcomes for the business.


Legacy system modernization is an update of outdated software that results in security improvement, new business opportunities, reduction of maintenance and updating costs, and easier integrations.  

Legacy system modernization has a range of challenges, such as costs, new security regulations, the numerous solution options, duration of the project, and new user experiences. Yet, the benefits of modernization far outweigh the challenges.  

You can take several approaches for the modernization of legacy systems: encapsulation, replatforming, refactoring, rearchitecting, or rebuild. If you still have some questions on which approach would work best for your business, or how to start writing your legacy application modernization roadmap, feel free to consult with the ModLogix experts. Book a call with our team and let the professionals create the best possible modernization strategy for your software! 

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