Tech Insights / Application Modernization

Application Modernization:
What is Application Modernization?

Application modernization is the process of updating legacy software to take advantage of the benefits of modern computing platforms and infrastructure. Legacy application modernization and the adoption of modern development methods are important for companies that want to become more agile and thrive in the digital age.

What are legacy applications?

Legacy applications were built with architectures and methods that are now considered outdated. Many of them are monoliths with all services and features packaged together in a single executable. Because these applications lack modularity, adding new functionality in one area may create regressions in other areas. Testing is complicated, maintenance is difficult, scaling is inefficient, and scaling beyond a certain limit can be all but impossible.

Strategies for modernizing applications

The first step in modernizing a legacy application portfolio is determining the degree of effort necessary to achieve the desired benefits for each application. Evaluate each application in terms of its business value and the technical feasibility of modernizing it, then focus most of your effort on applications that have high business value and are feasible to modernize.

There are three basic approaches to modernization, shown below in order of effort required from easiest to hardest:

Lift & Shift: Rehost Applications

Rehosting is the process of taking an application from its old infrastructure—such as an on-premises server—to new infrastructure—such as a public cloud—with minimal or no changes to the code. This is the least intensive approach but not always optimal depending on the application, since you end up with the application running on newer infrastructure but with the same set of application limitations.

Replatform: Cloud migration

Replatforming strikes a middle ground between lift-and-shift and complete refactoring. It entails updates to take advantage of a modern cloud platform, such as modifying or replacing an application’s backend database. It does not involve major changes in code or architecture.

Refactor: Monolith to microservices

Refactoring is the best approach when you have an application that needs to be fully modernized. It entails taking a legacy application and restructuring and re-writing significant chunks of the underlying code to run in a new environment, usually a private or public cloud. Monolithic applications are broken up into separate, decoupled pieces—an architectural approach called microservices. A microservices approach can maximize the benefits of cloud native infrastructure and tools and help accelerate new feature delivery and improve software quality. However, refactoring is also the most time-consuming and expensive approach, so it may not be appropriate for every legacy application in your portfolio.

Benefits of application modernization

Whether your target application is an e-commerce monolith, a critical financial application, or some other business-specific application, the process of application modernization encompasses the whole range of things you can do to an application to:

Simplify management and maintenance

Test the app more efficiently

Ship new versions more quickly

Scale the app more easily

Utilize modern infrastructure

Decrease costs

The goal of application modernization should be to deliver the specific set of benefits you need, not all possible benefits. Modern, well-architected apps can help you achieve your goals and solve a wide range of problems, future-proofing your enterprise by enabling greater agility, increasing the cadence of feature delivery, and enabling you to take advantage of cloud infrastructure.

VMware Tanzu delivers the expertise and advanced tooling to help you on your modernization journey. Advantages include:

Modernize apps in weeks

With VMware Tanzu you can adopt a modernization methodology that leverages cloud native patterns and continuous delivery (CD) automation across your existing application portfolio and benefit from meaningful modernization progress in weeks rather than months or years. Our iterative approach to modernization starts in a small, focused way and defines incremental steps that gradually increase the cloud maturity of existing systems.

Enhance business agility and productivity

Tanzu helps developers deliver modern apps faster with the resources they need to capitalize on critical cloud native technologies, including modern tooling, CI/CD pipelines, and Kubernetes.

Scale & automate production

Unlike monolithic applications where development and scaling activities are always tightly coupled, a microservices architecture built on Tanzu allows independent development, scaling and automation of each application component.

Cost effective solution

VMware Tanzu application development and modernization solutions provide a cost-effective solution for transforming your business, providing a platform that enables you to increase modernization over time to achieve targeted benefits.

What are the challenges of app modernization?

The sheer volume of code at most large organizations makes declaring modernization victory nearly impossible.

Complexity of modernizing

Organizations struggle with rapid growth in application volume, diversity of application styles and architectures, and siloed infrastructure supporting each application. Add to that the challenge of hard-coded interfaces to systems of record and the complexity of multi-cloud operations, and your organization can quickly feel overwhelmed.

Cost of modernization

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Many organizations are put off by the cost of large-scale modernization. But, there are significant direct costs associated with maintaining large legacy applications, not to mention lost opportunity costs or the impact of accumulating even greater technical debt. Code that is hard to change gets costlier over time. Successful modernization of important applications will deliver a rapid return on investment (ROI).

To succeed, organizations need to take a pragmatic approach to modernization.

What technologies are necessary for app modernization?

Application modernization usually involves the following set of technologies.

Cloud computing

Cloud technologies figure prominently in application modernization, enabling fast, flexible and elastic access to infrastructure resources to address development and production needs. In a private cloud, services and infrastructure are hosted privately, often within a company's own data center, and are not shared with other organizations. Public cloud refers to services and infrastructure from a public provider such as AWS, Microsoft Azure, Google Cloud, and other well-known providers. A hybrid cloud combines private and public cloud services, while the term multi-cloud is used to describe the use of multiple private and public clouds.


Containers offer both efficiency and speed compared with standard virtual machines (VMs). Using operating-system-level virtualization, a single OS instance is dynamically divided among one or more isolated containers, each with a unique writable file system and resource quota. The low overhead of creating and destroying containers combined with the high packing density in a single VM makes containers an ideal compute vehicle for deploying individual microservices.


Kubernetes is a portable, open source container platform that eliminates most of the manual processes involved in deploying and scaling containerized applications. After designing it, and running it internally for 15 years, Google open sourced the project in 2014 to the Cloud Native Computing Foundation (CNCF), which currently manages it.


Microservices is an architectural approach to developing an application as a collection of small services; each service implements business capabilities, runs as a separate process, and communicates via HTTP APIs or messaging. Each microservice can be deployed, upgraded, scaled, and restarted independent of other services in the same application, typically as part of an automated system, enabling frequent updates to live applications without impacting customers.

App modernization case studies

Logo DICK'S Sporting Goods was struggling with legacy applications that were slow, fragile, and expensive, requiring heroics on the part of the IT team to operate and still failing to deliver the desired user experience. The company initiated a significant modernization effort in 2017, resulting in faster time to market and meaningful improvements for its business.
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Logo Many companies prefer to start with changes that have immediate visible impact. Travelers Insurance chose to modernize its ratings engine because it is essential for quoting competitive insurance rates. The decades old rating engine was part of a monolith running on a mainframe. This made it difficult to scale, expensive to run, and reliant on a shrinking pool of engineers.
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Frequently Asked Questions

What are the important patterns of application modernization?

Three common patterns for modernizing applications include lift and shift, also known as rehosting, which is the process of taking an application from its old infrastructure to new infrastructure with minimal or no changes to the code. Another typical pattern is replatforming that entails updates to take advantage of a modern cloud platform. The final pattern is refactoring, which is the best approach when you have an application that needs to be fully modernized.

Why modernize legacy applications?

Updating legacy software with application modernization allows your enterprise to take advantage of modern computing platforms and infrastructure benefits. Legacy application modernization and the adoption of modern development methods are essential for companies that want to become more agile and thrive in the digital age.

What are the key technologies for application modernization?

There are four key technologies fundamental to application modernization, including containers, microservices, orchestration and automation, and cloud computing, which entails public cloud platforms, private clouds, and hybrid clouds.

What are the benefits of application modernization?

There are many benefits of application modernization including enhanced business agility and productivity, scale, and automation.

What are the challenges of application modernization?

Many organizations are put off by the cost of large-scale modernization and struggle with rapid growth in application volume, diversity of application styles and architectures, and siloed infrastructure supporting each application.