How To Approach Legacy System Modernization

Know in-depth about the approach to legacy system modernization. Evaluate legacy systems, select app modernization approach, Retain/Encapsulate, and more.

Legacy modernization aims to meet the organization's current business needs by enhancing business agility with new functionality and appealing features, strengthening customer service, and increasing efficiency.

However, modernizing a legacy system is not child's play, as nearly 74% of enterprises fail to complete legacy modernization processes due to a disconnect between technical and leadership teams.

Adopting the below-mentioned approaches can drive your modernization efforts in the right direction.

How to Approach Legacy Modernization

1. Evaluate Your Legacy System

You should concentrate on six major drivers when evaluating your legacy systems. The top three evaluation factors are business value, agility, and business fit. In addition, you must make sure that your legacy application has the agility to keep up with shifting markets or the ability to fulfill changing business requirements.

Three factors of evaluation - cost, complexity, and risk are all seen through the lens of IT. First, you must determine the total cost of ownership, the complexity of the technology, or security lapses. Then, you can easily determine whether your legacy system needs modernization by considering these six main drivers.

2. Select the Apt Modernization Approach

Select the correct application modernization approach after assessing project requirements and analyzing relevant case studies. Generally, companies may choose to rehost or refactor applications to operate them on the cloud. However, some applications may need to be rearchitected or replaced with SaaS-based systems as per business criticality.

3. Choose the Right Modernization Partner

When working on enterprise application modernization initiatives, keep in mind that people and culture are just as important as technology. You can work with a reputable software partner who has experience modernizing legacy systems and re-engineering them.

Instead of maintaining and updating onsite using waterfall software development procedures, many legacy application approaches concentrate on moving monolithic, on-premises applications into cloud-native architecture. However, to ensure a quicker time to market for your modernization project, you should look for a software development team that makes use of Agile and DevOps principles.

4. Retain/Encapsulate

It's a low-risk method that utilizes the legacy application's components in the new design. The legacy program is encased or wrapped, and an API is used to access it as a service. This method also introduces the ability to expand the app using a microservices structure gradually.

  • Rehost: Rehosting means "lift and shift" application components to another infrastructure.
  • Replatform: This method transfers the current code to a new platform, making minor code changes while keeping the present code's structure, features, and functionalities.
  • Refactor: Refactoring goes a step further by optimizing the code and reorganizing it to reduce some of the technical debt that could cause problems with legacy software. This debt can be caused by out-of-date libraries, frameworks, code, or incomplete or ineffective functionality.
  • Rearchitect: To rearchitect a legacy application is to significantly alter the code to shift it to a new architecture with greater capabilities.
  • Rebuild: Redesign or rewrite the application from scratch without changing the scope or specifications.
  • Replace: When a legacy system stops functioning for numerous business reasons, it's time to reorganize, understand the issue, and identify the best product to address it. This strategy will retire the legacy application, and a thorough product development process will be used.

5. Pick the Right Application Modernization Approach 

To pick the right solution from a plethora of options, you need to go beyond just effort and evaluate options based on terms like - workload, architecture, cost, risk, operations, and security. The weightage of each of the above parameters depends on the priority of the organization. 

6. Observe, Iterate, and Optimize

No one is picture-perfect in this world. After a project has begun, it is bound to go through multiple iterations. Going through multiple iterations ensures that the application's modifications are optimized with no kinks whatsoever in hosting, software licensing, or connectivity between other services. 

Key Technologies for Application Modernization

The above-said strategies of Legacy Application Modernization are implemented by leveraging several key technologies. 


Application modernization often involves moving or migrating applications to the cloud, a process known as re-platforming or rehosting. This can allow organizations to take advantage of the benefits of cloud computing, including increased scalability, faster deployment, and cost savings. There are various options for cloud deployment, including public clouds, private clouds, hybrid clouds, and multi-cloud environments.


Legacy applications often have a monolithic architecture, meaning they are one large, self-contained unit. A key goal of modernization is to increase flexibility and responsiveness to changing customer and employee needs. To achieve this, many organizations adopt a microservices approach, which involves breaking down an application into smaller, independent services that communicate via APIs. This allows organizations to easily swap out individual components or scale specific services as needed to meet evolving expectations better.

Orchestration and Automation 

Automation allows for the independent execution of specific tasks, whereas orchestration coordinates the automation of multiple tasks as part of a defined process or workflow. Both automation and orchestration bring about improvements in terms of deployment, scaling, networking, and security.


Legacy modernization can be a challenging but necessary task for businesses looking to stay competitive in today's fast-paced digital landscape. By understanding the scope and complexity of the legacy systems in question, utilizing modern technologies and methodologies, and involving stakeholders throughout the process, organizations can successfully modernize their legacy systems and realize the benefits of improved performance, scalability, and security. Remember that the goal of legacy modernization should be a comprehensive, flexible, and efficient IT environment. Through proper planning and execution, businesses can overcome the hurdles of legacy modernization and thrive in the digital age.

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