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Software Modernization

Escape the Burden of Legacy Software – Or How to Fuel the Success of Your Product

Published: Mar 26, 2022Last updated: Jun 29, 2022

More often than not, businesses find themselves trapped in their old legacy systems that no longer fulfill the purpose they were built for. In this article, we'll take a look at what legacy software systems are, and how software modernization can help to overcome the struggles that come with them. We'll also go through different approaches and emphasize on which best practices to follow. At the end of the article, you'll find highlights on the business benefits of such a transformation.

What Is Legacy Software?

A legacy application, as defined by Gartner, is "an information system that may be based on outdated technologies, but is critical to day-to-day operations". But it's a lot more than that. Such a software is considered obsolete, because it is underperforming and it doesn't meet the expectations of its users. It might still function as per the initial requirements that the organization had before the development of the system, but it struggles to remain relevant over time.

What Is Legacy Software Modernization?

A scared woman looking at computer screen warning message for a detected legacy software

Legacy software modernization or just "software modernization" is the process of rebuilding a legacy system from scratch or transforming the existing one into a more flexible, up-to-date solution that is in compliance with the company's objectives and goals. It also allows for a smooth transition that mitigates the risks of using an application that doesn't correspond to the business' ideas anymore.

The Burden of Legacy Software

When a legacy system fails to satisfy the demands of a growing organization, it is time for it to be modernized. This will keep the company on the market's competitive edge and provide greater business value. Although such an upgrade requires a decent amount of investment, legacy software is also very expensive to support and maintain. Moreover, if not addressed on time it leads to missed business opportunities, loss of potential customers, inability to respond timely to user feedback, poor team performance, etc.

How to Determine if a Legacy System Represents a High Risk for the Business?

A man trapped in a jar by a large rock representing the burden of legacy software, which is blocking the jar opening with a few icons around the jar

Analyzing the current state of an existing software is a complex task. It involves not only the tech expertise of a software development company, but also the know-how of people from within the organization. The ones using the application are most likely to know the challenges that come with it. So, a simple discussion with each one of them, may give you some answers and tilt the scales. The following criteria can act as a guide through the decision-making process of whether it is time for an existing application to be transformed and modernized. In essence, they define the burden of legacy software, so keep reading:

  • Not flexible enough to add new features
  • Difficult or impossible to adapt to new requirements
  • Data is stuck in silos and third-party integrations require a lot of effort
  • Lack of progress and inability to keep up with the competition
  • Substantially degrading performance
  • Decreased efficiency and productivity
  • Poor code quality
  • Manual deployment process including a lot of non-automated steps
  • Lack of unit tests and low code coverage
  • Vulnerability to frequent cyber attacks or the presence of security breaches
  • The use of outdated security protocols, standards and cryptographic mechanisms
  • Shortage of qualified development staff or one that requires a specific set of skills and expertise to support the application
  • Non-compliance with modern regulations or inability to adhere to them
  • The use of outdated technologies
  • Impossible to update to newer versions of the used technologies
  • Incompatibility with new systems that are essential to the organization
  • Unsatisfied users, loss of customers, and bad company reputation
  • Expensive maintenance
  • Lots of issues and bugs that are hard to fix, or when fixed lead to more bugs
  • A lot of workarounds to get something done, especially when a third-party solution can do the job
  • Inability to adapt to the changes in the economy or the fast-evolving market
  • Frequent delays of rolling out new functionalities
  • Frequent system disruptions
  • Hard to scale up or down, depending on the traffic
  • The software development company or the software vendor can no longer provide support and maintenance
  • Low staff retention rate, lack of motivation to use the application

If one or more of the aforementioned issues are present in a software product, it can be ultimately called "legacy". It is right about time to modernize it and to start keeping pace with the demands of the digital market. Failure to do so, and continuing the use of the old solution will inevitably create unnecessary expenses and will appear as a risk liability. In this fast-paced technological world, companies are forced to adapt and improve even more than before.

What to Consider and How to Prepare?

Software modernization is a time-consuming process that needs an iterative approach. Adopting agile software development can speed up delivery and provide value faster than with the traditional waterfall model. Coming up with a detailed action plan is a vital part of minimizing the potential risks of this transformation. It's of great importance to make a thorough assessment of the legacy application's condition, its functionalities and flaws. This will help with the preparation of a transition roadmap that is in accordance with the current business requirements and the chosen modernization strategy.

There are a few questions that should be considered while outlining a timeline, such as:

  • Is the existing legacy system critical to your business, i.e. what will happen if it suddenly stops working?
  • Are some departments of your company more reliant on it or more influenced by it than others?
  • Besides your staff, are there any third parties (e.g. customers, partners, etc.) using the software and how often do they use it?
  • Is this legacy application providing any value to your business? What value do you need and how is your current software not compliant with that?
  • Are you able to perform your daily activities and complete your tasks with the current state of the application? If not, what are the main challenges that you are facing?
  • What is the user experience and are there any issues that users report while using your solution?
  • Do you have a systematic and detailed assessment of the technologies, code quality, and software architecture of your application?
  • What are the future business goals and how do you envision the software helping with the fulfillment of those objectives?
  • How is the current infrastructure organized in terms of scalability and deployment?
  • Which are the most important features that your organization can't manage without?
  • Is the security of the application endangered? Are there any security or data breaches that need to be addressed with priority?
  • Do you have any technical documentation about the changes that were made during the development of your legacy system?
  • How much time and budget does your company have for the modernization process?

Analyzing the answers to these questions and evaluating any other technical details, will help the software development team to make a final decision on which modernization approach would be most appropriate for the project. They will choose the necessary technology stack and qualified specialists that will deliver results faster with more added value.

Once a timeline is established, and it is approved by all parties, the process of modernization can be started. Meanwhile, companies must coordinate the changes with their personnel and should organize internal training and coaching sessions to ensure that everyone is on the same page.


There are 2 main approaches when it comes to software modernization - revolutionary and evolutionary.

1. Revolutionary Approach

The revolutionary approach, also known as "Big Bang Rewrite" or the "Rebuild" technique, is the process of building a completely new system from the ground up that is meant to replace the old system at some point in the future. This is a non-effective method of modernization as it imposes an extraordinary risk for the organization. Using it makes it hard to do estimations, make predictions, or get early feedback from adopters. It also requires a very comprehensive and exhaustive list of features that need to be implemented. By the time the new application sees the light of day, it is already going to be obsolete. In essence, a Big Bang Rewrite is not advisable and should be your very last resort.

2. Evolutionary Approach

Evolutionary modernization refers to a multi-phased approach to transforming legacy applications. Instead of doing a full rewrite, the focus here is on the constant improvement and evolution of the software architecture. The emphasis is on how it can be changed to better reflect the requirements, deliver a greater user experience and increase customer satisfaction.

Refactoring an existing solution is an ongoing process that is usually performed by experienced developers. They should have a thorough understanding of the functionality that is being refactored and need to have a good plan to start with. A mistake that many teams make is that they think of it more as a technical migration, instead of focusing on the organization's domain and internal processes. As a result, they build a completely new feature, which works the same way the old one did, except it's written in more modern technology. This brings absolutely no added value and, if not combined with an actual restructuring of the business logic, it is a pure waste of time and resources.

Adopting agile software development principles is the key to successfully implementing the evolutionary approach. This is a long-term model that spreads the development costs over time. It is also a bit slow-paced, but reduces system disruptions and enables the seamless growth of the product. All of this is possible when the strangler pattern is applied. The term was coined initially by Martin Fowler, and allows for an incremental replacement of the legacy system by gradually rewriting parts of the existing features. This can continuously provide value and give the team the opportunity to make regular software releases, and thus enable the company to supervise the progress more thoroughly.

Techniques for Iterative Modernization

Being faced with the challenge of modernizing legacy software, the best techniques to use depend on the problems that the organization is trying to solve. The key moment is to get to know the problems carefully and analyze whether they are caused by the implemented business logic, the software architecture or infrastructure, or another technological aspect.

Talking about iterative modernization, there are a few techniques that can be applied or even combined according to the situation. The right strategy is determined by many factors, including the expected timeline, ROI, budget, etc.

1. Encapsulate

This refers to the encapsulation of the application's data and functionality and only exposing them through a facade in the form of an API. For example, this technique makes it possible to create a new user interface without changing any of the underlying logic and structure of the legacy system.

2. Rehost (a.k.a. "Lift and Shift")

This involves the redeployment of the existing application or parts of it (whenever possible) to a different infrastructure (e.g. to a cloud-based solution) with little to no code alterations. In some cases this could include database migrations as well.

3. Replatform

It is the process of migrating to a new runtime platform with minimal code modifications. While it might be similar to the Rehost technique, some additional changes are made to take advantage of the new cloud infrastructure. It might also include the automation of some repetitive tasks related to the deployment of the application.

4. Refactor (a.k.a. "Code Refactor")

Usually it means updating the existing code to deal with technical debt and to optimize for better performance, while the rest of the application stays the same.

5. Rearchitect

It represents major changes in the code that aim to avoid scalability issues. This is ensured by doing a migration from a monolithic application to microservices. It contributes to better separation of concerns and embraces agility and innovation. Although it is the most time-consuming type of technique, it has proven itself to be the most effective one.

6. Replace

This is the act of eliminating a whole application component or module, and replacing it with a new one. While it only focuses on an isolated part of the software, it is similar to the Big Bang Rewrite approach and should be avoided due to the risks it carries.


Wooden cubes representing a ladder to business success with three words next to it: Innovate, Adapt, Succeed

The business can definitely benefit from a legacy software modernization. Enlisted below you will find some of the positive effects of such a transition:

  • Being on the competitive edge of the business market
  • Improve the user experience
  • Gain more trust, boost brand awareness, and attract new customers and partners
  • Implement better security practices and prevent data breaches
  • Streamlined business processes, operational efficiency and increased productivity
  • Higher ROI
  • Solid ground for future innovations
  • Reduce time to market and deliver value faster
  • Technical flexibility and ease of integration with other service providers
  • Low employee turnover, more motivated people that are eager to work and learn
  • Enhanced software quality that ensures less system disruptions

Final Thoughts

It's easy to come up with new ideas; the hard part is letting go of what worked for you two years ago, but will soon be out of date.

Roger von Oech - speaker & author

Software modernization is the backbone of every business. So, don't be afraid to let go of your legacy system. Experiment with new ideas. Be an innovator, because by embracing innovation you fuel the success of your company, which helps you stay relevant and stand out from your competitors.

  • legacy software
  • risk mitigation
  • agile project management
  • custom software development
  • business strategy

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