Tech Content
8 minutes

Digital transformation’ has been one the most commonly used phrases in the last few years. For many, it has become an umbrella term that explains the changes across industries as they include technology in their services.

However, many companies forget that software doesn’t improve over time. We live in constant change; old operational systems are quickly replaced by new ones, and underperforming and outdated software can quickly become a major barrier in business development. 

All legacy systems require modernization as they become more prone to bugs, crashes, and safety issues over time. Such software is hard to maintain, improve, support, or even integrate with new systems. Because of this, legacy software is often seen as the greatest obstacle to digitalization and modernization. 

In this guide, we will share the importance of legacy software modernization, the advantages of this approach, and why you should consider utilizing it. Some of the key aspects we’ll focus on is software reengineering and why it is necessary, as well as what approaches our clients can take to be sure they are doing it right. 

What is Software Reengineering? 

A legacy application is a system based on old technology but is essential for all operations. Based on this, a legacy infrastructure system update refers to updating and replacing an outdated system, processes, or application fully or partially. 

Software reengineering is focused on the analysis and modification of legacy software code. However, the greatest role it plays is enabling the modification of legacy infrastructure which helps to maintain software. 

The reengineering process contains three main aspects: 

  1. Understanding how the legacy software works with all its specifications and requirements
  2. Mapping out the necessary modifications to be made
  3. Removing the unnecessary parts of the legacy code
  4. Re-writing of the code

Every software reengineering process begins with understanding the current system. Once a Business Analyst and Solution Architect have audited the current system specifications and system requirements, they will gain a deeper understanding of its architecture to be able to recommend the right solutions for future development.

The next step is to find concrete ways to improve the system’s structure and the right places to add modifications. Software modifications don’t have to be major, but if the software is outdated, then it might be necessary to perform rewrites, reconstruction, and modularization.

Finally, removing old code is an important step in ensuring the stability of legacy code. Once the code is updated, it becomes possible to add new functionalities and continue its development. 

Why Should You Update Your System?

Eventually, every software needs modernization. That doesn’t mean companies should rewrite every application once every ten years, but pretty much every system requires updates to stay efficient, quickly respond to market changes, and eventually increase ROI.

Usually, maintenance and support costs surpass the price of code moderation, which involves updates, infrastructure, staff training, and security. 

Improved Security

Legacy systems are an easy target for cybercrime. If you are using the same code, hackers will have enough time to reverse engineer and find weak points. Lack of regular maintenance inevitably leads to lower levels of security, inefficiency, and potential security breaches that can harm your business. 

Easier Integration and Compliance

Modern software heavily relies on third-party APIs to enable them to offer better services. Third-party software can be involved in many different processes. However, if your code can’t integrate, you will be spending more time and money to create custom-made solutions and connect them to third-party software. 

Gain New Business Opportunities

Improving IT infrastructure is usually associated with additional expenses. Regardless of the type of investment, when money is spent on one thing, it means that there is less available for research and improvements. Continuing to invest in obsolete tech or clinging to old software might prevent you from capitalizing on new opportunities or business expansions that your competitors are already doing. 

How to Approach Legacy System Modernization

Adding new technologies to every aspect of a business is an essential part of growth. Each application needs to be modernized at one point or another, so entrepreneurs must find the most effective way to do it. This usually requires understanding the risk-to-reward ratio before acting and deciding on the right approach. 

According to research from Gartner, there are six main drivers for application modernization. All of them are the result of specific functionality, code architecture, and technology. 

Analyzing a product's business and technological aspects makes it possible to see the bigger picture, which is needed to plan development steps forward. The six main drivers of legacy system modernization are: 

  1. Business fit
  2. Value 
  3. Agility 
  4. Cost
  5. Complexity
  6. Risks involved in such a project

How to Choose the Best Software Modernization Approach

When you decide to modernize, you must be ready to take on more than you expect. Since there is no one-size-fits-all approach, you must take the time to analyze and prepare for software modernization properly. 

When deciding which method to use, think about the highest value you can add to your organization by mapping out all of your options, in particular how they influence the software architecture, functionality, costs, and risks. Before making a final decision, your analysis should incorporate information about: 

  • Existing tech stack
  • Application functionalities
  • Project complexity
  • Potential risks
  • Overall project cost

Finally, modernizing legacy software means deciding whether you want to rebuild, replace, or re-architect. While reconstruction and replacement provide the right balance with the best results and minimal risks, rearchitecting has the lowest chance and medium-cost levels. 

Planning and development stage of software reengineering

Different Strategies for Software Reengineering

Updating your legacy system is not an easy task as stakeholders often see it as a massive undertaking. However, it can bring a lot of value since it allows companies to serve new clients better and offer them improved services and more flexibility. Modernization can be done in several different ways, and each type comes with its own risks and different levels of business impact.

Once you decide to engage in software reengineering, there will be different modernization options to choose from. Making a decision is not always simple, but it needs to be based on the understanding of the risks and business impact each of the strategies will have.

Keep in mind that modernization doesn’t always require a complete transformation but it should focus on prioritizing which aspects of your software should be improved before others. After analyzing existing IT infrastructure, technology, functionality, risks, cost, and the complexity of your system, you will have a better idea of which approach would work best for your case. 


You can change the app infrastructure from physical, virtual, or cloud without needing to modify its code. The rehosting strategy includes migration of your system to the cloud to make it more flexible or moving to SQL-based architecture. The benefits of this approach include keeping your business intact while lowering the cost of maintenance.


Developers can restructure and optimize the current code to improve non-functional attributes. Plus, cleaning up the code can increase its performance. 

Software Rebuilding

In some cases, it may be necessary for you to completely redesign and rebuild an application’s component while preserving the application’s architecture. 


Rearchitecting the code basically means fully changing it to adapt to a different architecture. If you decide to materially change the code and shift to a different architecture, you can take advantage of its improved capabilities.


By completely eliminating the previous application and replacing it with new code, you will be able to add new components and have increased flexibility that provides room for bigger changes.

Monolithic vs microservices architecture comparisson

Hidden Costs of Using Outdated Legacy Software 

Even considering the benefits of a switch, many companies continue to use outdated systems. Regardless of their quality or technology, they feel that if the software is working, changing it is an unnecessary expense. Indeed, as they say, ‘why fix something that’s not broken?’.

In reality, there are many reasons legacy systems need to be updated or replaced. The biggest being the cost of running outdated software. 

There are a variety of hidden costs associated with using obsolete software. The older the system, the more expensive it is to change specific modulus or add new functionalities. Here’s where you will be spending most of your money if you have a legacy system:

Maintenance costs can go over the original development budget in the first ten years after the release. If the legacy code demands ongoing maintenance from a team, the costs can quickly accumulate and create a hole in your budget. Just like the software, infrastructure maintenance spending can increase in time, especially if cloud-based solutions aren’t a good way to continue. 

Automatization can significantly reduce inefficiencies. However, this is the case only if the system has the capacity to introduce automation. Systems that cannot introduce automatization might face a noticeable decrease in their business profitability.

Integrations allow your system to work better with the latest software and hardware versions that come out. Modern applications are integration-ready from the start, and API vendors provide support for different frameworks. However, if you are using old technology, you won’t always be able to use that compatibility to your advantage.

Security is one of the biggest problems for anyone working with an outdated legacy code.If a vendor no longer supports outdated software, there will be no patches or solutions that will keep it compliant. Every data breach is costly and can create an even bigger problem once they are built up.

Benefits of Software Reengineering

Benefits of Software Reengineering 

Regardless of all the risks, there are still companies willing to use legacy code. Some businesses will only reconsider updating their system if an emergency occurs. Updating legacy systems has a reputation for being hugely expensive, taking an enormous amount of time, and even causing long system downtimes. 

In reality, this is not always true, and with a variety of tech stacks available, the process becomes easier to navigate. Still, it’s always important to have a skilled team working on reengineering efforts to decrease the chances of something going wrong. 

Operating in a fast-paced industry requires offering simple solutions that can outperform your competition. With a modern solution readily available and the ability to integrate, you can offer your clients exactly what they are looking for. 

The many benefits of reengineering legacy code prove that modernization is, and will be, instrumental in keeping up with the ever-changing demand from customers. By modernizing your legacy code, you will: 

  • Build a competitive advantage
  • Reduce maintenance costs
  • Stay ahead of the curve
  • Improve customer experience
  • Improve security
  • Take advantage of the newest versions of software and hardware

Reengineering Project Risks

Legacy software is important for every business, and some companies cannot simply remove these demanding systems. Replacing systems with SaaS solutions can help, but usually, they lack the agility and customization that big businesses need. And while developing a new application can sound very tempting, these projects are vulnerable to the many risks related to developing new software. 

Reengineering Project Risks

It is important when changing the legacy code to consider the loss of essential functionalities that might occur. 

The loss of managerial support and interest is another risk that keeps some companies from wanting to update their legacy code. As the benefits of reengineering projects are not immediately visible, managers tend to focus on more pressing matters, and may even cut funding due to more other issues they prioritize. 

Being able to project accurate costs, know the expected ROI, and understand what efforts are required is vital before proceeding with a legacy code update. With incomplete documentation or information prior to beginning an update, your calculations may be incorrect, and you may have extra time or costs, making your project goal more complicated and unattainable. 

Checklist for Successful Application Modernization

Legacy software is not simply “outdated” or “old”. There’s a lot more to it, and that's why every software reengineering process should start with a thorough assessment of all the systems to uncover all existing and potential problems. Here, we propose a helpful checklist our experts use for these projects:

  1. Understand your legacy system
  2. Pick the right approach
  3. Asses architecture and opt for simplicity
  4. Choose a reliable tech stack 
  5. Document everything you do
  6. Create a retirement schedule

Legacy Reengineering with Softjourn

Reengineering is integral for software evolution. Reengineering is almost inevitable if you want to significantly reduce maintenance costs for your legacy software, gain a competitive advantage with extended reach and functionality, and have a solid foundation for further modernization activities, such as moving software to the cloud or splitting a legacy application into microservices. 

However, reengineering legacy software is an intensive activity that, if done wrong, can result in high costs and unknown results.

If you are thinking about legacy software modernization and need help selecting the right approach that won’t disrupt internal processes - Softjourn can help. Our analysts and expert teams will provide all you need to gain a stable and customizable system that will support your growth.