Legacy Application Modernization - A Detailed Guide

21 December7 min read
Legacy Application Modernization - A Detailed Guide

Legacy applications are the bane of modern IT. By definition, they’re old and outdated, and they often come with a host of problems. That said, legacy applications are not always the devil they appear to be. In many cases, they’re perfectly capable of operating within the confines of your organization. The problem is that most legacy apps were built around some other software or system in use at the time—and that software or system has now moved on. These changes can make it difficult for IT professionals to keep these older systems up to date with current industry standards and practices. This challenge is exactly why you should take Legacy Application Modernization seriously as soon as possible. Here’s more about what this entails and why you should implement LAM sooner rather than later.

What is Legacy Application Modernization?

Legacy application modernization (LAM) is about bringing your existing legacy apps up to date with current practices and standards. This is a big reason why many organizations think about this process after a significant change such as moving or bringing an app online. Once again, understanding the challenges of a legacy app is the first step to making your legacy app modernization a success. This means that you need to understand why those challenges exist in your organization. This will help you determine the best place to start your modernization project. An important note: Legacy application modernization is not the same thing as legacy app modernization. As the name suggests, legacy app modernization is about making an application more modern or flexible by integrating certain cloud technologies. Legacy application modernization is about bringing an app up to date with current practices and standards, not about integrating particular technologies.

Why ​​is it so important to adopt Legacy Application Modernization?

  • It’s important to adopt legacy application modernization because it’s one of the best ways to improve your IT efficiency. That, in turn, will make your organization more resilient to challenges like cyberattacks.
  • Legacy application modernization will help you make your legacy apps more flexible, more secure, and more cost-effective. And these are just a few of the benefits of legacy application modernization.
  • In some cases, you can see brand new features and functionality enter your organization as a result of your legacy app modernization. You’ll also see a significant reduction in maintenance costs as the number of assets needing routine updates decreases.

The Right Approach to Legacy Application Modernization


  • This tactic, also referred to as the "lift and shift" idea, comprises moving the core components of your application from an on-premises data center to the cloud in their present configuration.
  • The infrastructure, which consists of cloud-based storage, compute, and network resources, is moved to cloud infrastructure-as-a-service while the application codebase is left unchanged (IaaS).
  • Current systems, especially monolithic legacy program, won't be able to benefit from important cloud-native features like PaaS, multi-cloud, microservices, agile methodology, containers, CI/CD, and DevOps procedures if they try to be migrated to a cloud architecture. However, this strategy works well if you're looking to save money and use the cloud as a disaster recovery option.


  • In the digital age, cloud-based applications are anticipated. To take full advantage of a public cloud, it involves changing the program itself and some code.
  • Developers can benefit from the strategic code of the company by reusing their investments in programming languages, frameworks, and containers.
  • Although it requires a lot of time and resources, the benefits far surpass these drawbacks. For some of the functional aspects, organizations take advantage of establishing independent services and make them accessible to both internal and external users.


  • This solution re-architects the legacy monolithic program utilizing the microservices approach, containerization, and current DevOps practices. This involves separating your monolithic program into a number of services that can be developed, released, and managed independently.0
  • It requires fundamentally modifying or breaking down the application into services as opposed to a complete rewrite. You have more control over the design process using this divide-and-conquer strategy, which also has benefits like business agility, a shorter time to market, cheaper costs, and the capacity to rethink the consumer experience.
  • The technologies used include serverless, containerization, microservices, cloud-based PaaS (if needed), and present DevOps techniques.


  • It's similar to a re-architecture, only that you're flattening it and starting over rather than remodelling. As with a home, starting from scratch can be more economical and typically yields a much better result than an effort at renovation.
  • During the rebuild, the programme is redeveloped as a cloud-native application, which helps to innovate, release value earlier, and reduce total operational costs.
  • Given the development of new technologies, languages, frameworks, and other efficiencies, it may have taken far more work to create the old programme than it would to replace it now. Nowadays, lower-level programming is often abstracted.


  • In some cases, if a legacy application offers some functionality that is still useful, you can replace it with a more adaptable cloud-based solution.
  • A straightforward example is shifting from an on-premises version of Microsoft Exchange Server to Office 365. Instead of being acquired as licences, many services are now offered as pay-as-you-go subscriptions.

How to start with Legacy Application Modernization

Step 1 - Start With Evaluation of Your Legacy Application

  • The first step is to assess your software environment and identify the key drivers of system modernization. These include analyzing how technology affects six areas: business process, data quality, security, compliance requirements, resource planning and management processes.
  • Modifying systems to support a company and help it address business opportunities
  • Optimizing software for KPIs completion in order to achieve business goals
  • Enhancing an organization's ability to adapt to the ever-changing business and technology needs.
  • Ways to bring down development/maintenance costs of software systems
  • Making sure codebase maintenance is affordable and does not cause too many issues such as bugs or downtime.
  • Strategies to minimize risks to systems’ efficiency, robustness and security.

Step 2 - Define objectives for modernization

  • The subsequent step in a utility modernization method is to assess modernization alternatives, i.e., techniques to modernize applications. You can keep in mind the alternatives given below:
  • Retain – A approach to retain/reuse legacy utility additives inside a brand-new structure.
  • Rehost – Redeploy or shift the utility factor elsewhere, i.e., to a different infrastructure (virtual, physical, cloud) quickly without enhancing its features, code, or functions.
  • Replatform – Migrate or flow the present code to a brand new platform even as reshaping the code while preserving the present-day features, code, and functions.
  • Refactor – Refactoring and optimizing the code and making fewer adjustments to the code to get rid of technical debt main to legacy software program troubles that would be frameworks, old libraries, code, or inefficient features.
  • Rearchitect – Rearchitecting a legacy utility way appreciably changing the code to shift it to a brand new structure with higher capabilities.
  • Rebuild – Rewriting/Redesigning the utility from scratch without converting the specs or scope.

Step 3 - Consider the resources available.

While thinking about resource allocation, meticulously plan a while and budget. More precisely, seek advice from the ones who've already skilled hit transformations. Many groups enjoy demanding situations with organization system modernization due to the uncertainty associated with the whole value of ownership.

Step 4 - Decide the Way to Approach

The next application modernization method is to list short/long-time period measures. The fine approach to begin the app modernization adventure is to head for a code review. It facilitates smoothing up the present code base, perceiving regions requiring improvements, and attaching bugs. UX audit is any other modernization approach that analyzes qualitative/quantitative and behavioral records approximately device usage

Step 5 - Modernize Your Application

While modernizing the application for customers or different enterprise partners, keep in mind that they're familiar with the blessings they may get hold of from the change. Besides, all of the essential guides might be supplied at the same time as onboarding to the brand-new platform.

The challenges of a legacy app

During this analysis, you’ll want to understand the technical challenges facing your legacy app. This will help you identify the ones that are most important to your organization. You may also find that you’re able to address one challenge while choosing to ignore another. Once you understand the challenges facing your legacy app, you can begin the process of developing a modernization roadmap. This roadmap can help you determine the order in which you’ll bring your legacy app up to speed.

LAMS and their benefits: what you’ll find in a good one

  • A good legacy app modernization will help you modernize your legacy app with a variety of best-in-class technologies. This can help you bring your legacy app up to speed with current industry standards.
  • During your modernization, you may also find that your legacy app can use some combination of these technologies in a single package:
  • Modernized technologies - These are the technologies that your organization is using now or will be using in the near future. In some cases, the organization you’re working with may be using these technologies and standards now. In other cases, they may not be using those technologies and standards at all.
  • Legacy technologies - These are the underlying technologies that make up your legacy app. These may include file formats, business rules, or other underlying principles.
  • Best-in-class technologies - These are technologies that have not yet achieved a certain level of critical mass in your organization or industry.

Key Takeaways

The good news is that you can modernize your legacy apps. In fact, it can be incredibly beneficial for your organization. As you take the first steps to modernizing your legacy apps, you’ll want to make sure you understand the technical challenges facing your legacy app. This will help you identify the ones most important to your organization.