Published May 24, 2022

Before we get started, we need to understand - what application modernization is. The terms application modernization or legacy application modernization describe the updation and redevelopment of an organization’s software to be deployed with contemporary computing approaches.

These may include cloud computing, new languages, updated frameworks, or the latest infrastructure platforms. The primary objective of application modernization is to build business value from existing applications by updating them with modern features and aligning them with evolving business needs and market trends. The decision to update your organization’s applications is only the first step. The next is picking the application modernization strategy that best suits your business needs and fits your organization’s growth trajectory.

There are five key migration options, commonly referred to as the five R’s of cloud application modernization:

  1. Rehost
  2. Refactor
  3. Re-architect
  4. Rebuild
  5. Replace

It is imperative to know the advantages and limitations of each strategy to decide which one will best suit your specific needs. We’re going to take a closer look at each of them here.

The 5 R’s of Cloud Application Modernization


This approach to cloud migration is also referred to as the “lift and shift” model. As the name suggests, it involves moving an application’s underlying resources from an on-premises server or data center and redeploying these resources as-is to the cloud.

This approach leaves the application codebase unchanged. The storage, computing, and network infrastructure are migrated to the cloud on an infrastructure-as-a-service (IaaS) model.

The primary advantages of the rehosting approach are ease of implementation and greatly reduced IT outsourcing costs. However, it severely limits flexibility.

Leaving the application as-is fails to take advantage of some extremely useful cloud-native features such as platform-as-a-service (PaaS), agile methods, multi-cloud deployments, containers, and DevOps practices.

Other drawbacks to this approach include high cloud service costs when migrating monolithic legacy applications, potential security issues, and higher downtime. Rehosting is an acceptable approach when dealing with less strategic applications.

One might want to consider other options when dealing with core business applications.


Refactoring involves modifying applications to ensure better performance in the cloud environment without changing their inherent behavior.

The codebase remains mostly unchanged with this approach and is migrated to cloud IaaS, including computing resources, cloud-based storage, and network resources.

This method ensures better cloud resource utilization and allows for the addition of new features or modifications to existing functionality. It also shares several shortcomings with the rehosting approach and needs more time to get right.


This approach to application modernization follows the microservices model. Rather than completely rebuilding the application, this approach involves breaking down legacy monolithic applications into a compilation of services that can be built, managed, and deployed independently of each other.

Offering greater control and business agility than the previous two methods, this approach leverages newer technologies like cloud-provided platform-as-a-service (PaaS), containerization, and modern DevOps practices.

This model eliminates data center costs and proprietary software licenses and saves the time and resources spent maintaining old infrastructure.


Completely rebuilding an application from the ground up as a cloud-native application can deliver the best value among the five methods of application modernization mentioned here.

This approach returns the greatest benefits of the cloud and greatly reduces overall operational costs. It is especially valuable when dealing with applications that can provide an organization with a competitive or strategic edge.

While completely rebuilding an application might sound cumbersome, this usually isn’t the case. In fact, with advancements in technology, languages, programming, and frameworks, rebuilding may require less effort than building the legacy application in the first place.


It may be possible to replace some legacy applications with nimbler and streamlined cloud-based options that work better with modern operating systems and cloud computing infrastructure.

Using a software-as-a-service (SaaS) model means that your organization can switch from purchasing software licenses to pay-as-you-go subscriptions, potentially saving costs.

Vendors develop these applications to be used through the cloud, handle the underlying infrastructure, and provide support. All you need to do is plan, maintain, and develop the application for end-use.

Additionally, this approach offers better security and eliminates the need for frequent updates as you always have access to the latest versions of cloud-based applications.

Final Words

Today, more and more businesses are taking the leap toward migrating their operations to the cloud. While deciding on the perfect approach to legacy application modernization may seem daunting, the process can go smoothly with the right tools and resources at your disposal.

Zensa offers comprehensive application modernization services to suit the needs of most businesses. Get in touch to discover your organization’s perfect route to efficient cloud migration.