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Transforming your Business for the Digital Future: Legacy System Modernization

Laptop with code
digital transformation, legacy systems

Whether it's the 30-year-old mainframe system that can't be replaced because of its place in your organization's accounting infrastructure or the three-year-old Java application that nobody knows how to fix when it breaks, legacy systems are a fact of life for most organizations. Unfortunately, many problems plague legacy systems. Supporting, maintaining, enhancing, or integrating with new systems is challenging. They require a lot of maintenance, and replacing an outdated system is complex if it controls essential business operations within an organization.

Legacy system modernization can be expensive for large and small businesses. But this does not have to be the case. Answering a few key questions can reduce the effort and cost of upgrades while ensuring optimal functionality, performance, and user experience.

What Is Legacy System Modernization?

Legacy system modernization is migrating existing technology systems and solutions to make it more efficient and effective. By utilizing contemporary technology, legacy system modernization can boost your company's bottom line. But what does this mean? Systems that have been around for a while and are still in use are known as legacy systems. They were possibly created before smartphones and tablets and are typically older than ten years.

Because of their age, complexity, and expense, legacy systems frequently go unrecognized despite their importance to business operations. Because they are challenging to maintain or upgrade, legacy systems can pose a significant obstacle to your organization's efforts to undergo digital transformation. They might also necessitate expensive adjustments, like rewriting code or buying new hardware to replace antiquated ones.

A Methodical Approach to Modernizing Your Company's Legacy Systems

A structured approach to legacy system modernization entails asking two key questions and then deciding on the best approach based on the answers. It also entails making legacy system modernization a continuous process rather than a one-time event.

For many businesses, the most challenging part is making yourself and your teams answer questions methodically when you are confident you already know the answers. But the effort is worthwhile: The solutions often let technology experts completely avoid labor-intensive or unnecessary tasks.

1. What is your organization's definition of legacy?

Before you begin modernizing your organization's legacy systems, you must clearly define what constitutes a legacy system. This is a question of semantics, but it's also key to understanding the scope of your modernization efforts.

The term "legacy system" is often thrown around in the tech world, and its meaning can vary from organization to organization. For some, it's a simple description of an older system that still works well, whether because it's been updated over time or because you've decided not to replace it yet. For others, however, "legacy" is shorthand for a string of systems built up over decades, cobbled together through years of ad-hoc additions with little to no thought given to maintaining things in an organized way.

In determining which systems are part of your organization's legacy, you'll want to look at when they were built and how they evolved. What was the last time someone took a hard look at each piece individually? Did anyone have a plan in place? If so, how much work is involved in transitioning off of each one? Are there any unique circumstances that make it more difficult than usual? Your answers to these questions will determine which systems to prioritize and which to ignore for the time being.

2. What's the best approach for legacy system modernization?

Organizations like Gartner, AWS, and Microsoft have discussed the "Rs" of modernization in great depth: rehost, refactor, rearchitect, rebuild, replace. Each approach has its advantages and disadvantages but is not mutually exclusive. So which of the Rs is right for your organization? The answer might depend on the legacy system in question and its business value.


Also called "lift and shift, this  is a quick way to remain operational during the transition to new technology. The idea is to place your current system on a new platform without changing the programming or underlying logic. It's an option for organizations that don't have the staff or budget for a full-blown modernization project—but there are some pitfalls. First, you're still running the old code on a new platform so you're bound to hit compatibility issues along the way.

You also run the risk of cloud computing costs increasing as you get more people using your application. Finally, if your company has been using the same application for years, any bugs or security flaws have had plenty of time to develop. Other avenues like rearchitecting or rebuilding might result in better long-term success.


This is another option to improve your code's efficiency and reliability without making significant changes, such as moving from client-server to cloud architecture. However, refactoring alone won't help you achieve complete modernization; rearchitecting is necessary. Rearchitecting involves a complete overhaul of an application, including its data processing functions, business logic, and user interface. Rebuild is also worth considering if you need a more efficient architecture or agile processes. In this case, you would start from scratch with new design and architectural principles in mind.

Rearchitecture or Rebuild

The rebuild option often means building a complete replica of your legacy system in a new language or framework and then migrating over data and functionality piece by piece until you've reached 100% replacement. This is time-consuming and expensive, but having the resources at your disposal might give you more control over the specific tools you use and the final result. On the other hand, doing a rewrite or re-architecture means making changes to your legacy system right away and implementing them as soon as possible—they'll be done differently, and you won't have all of the same functionality initially. Still, they're necessary steps in creating a more nimble system in the long run.

That said, rearchitecture and rebuilding are less straightforward than they sound. For example, suppose your goal is to update a legacy system's performance and security capabilities without disrupting users or applications. In that case, you'll need to consider how much time and money you're willing to sink into this effort.


When your business can no longer support a legacy system, you may have to replace that application. This is an excellent opportunity to examine the problem and evaluate solutions for a product that will solve that problem. The approach is collaborative, allowing the development of a new product in the most efficient manner possible.


Final Thoughts

As a general rule, the best approach for modernizing legacy systems is the one that most closely aligns with the goals and objectives of your organization. But how do you know which approach is best? The answer to this question depends on a range of factors, including cost, timing (i.e., how quickly does the modernization need to happen), the number and type of other legacy systems that need modernizing, and your company's overall business strategy.

As you evaluate your options, consider what makes sense for each system and how all of them fit together into your company's overall plan for modernizing its legacy systems.

Rather than asking, "How can we modernize all our legacy systems?" it is more constructive to ask, "Where are we in terms of where our organization needs to go?" This will help set up your roadmap for modernizing all systems -- not just those currently classified as legacy. As part of that roadmap, it's essential to include a regular review of all systems to determine when they slip into the legacy category.

Keeping track of all this can be difficult, so many companies choose to develop a formalized process for maintaining their overall modernization roadmap. A roadmap helps you establish a long-term vision for modernizing your legacy systems and evaluate your short-term options in light of that vision. Need help creating your legacy system modernization roadmap? Provisio can help you make informed choices about which approach will provide the most effective modernization solutions and achieve your overall business objectives.