Legacy application replatforming explained: Strategies & benefits.

Business and technology leaders view complex legacy technology as a major bottleneck to digital-first business strategies, especially as cloud and AI adoption and customer experience expectations continue to rise.

While legacy application replatforming can be a complex process, enterprises often benefit from improved scalability, operational agility, strong digital experiences, and lower long-term infrastructure costs.

Why do enterprises replatform legacy applications?

For large enterprises, legacy application replatforming requires migrating hundreds of legacy applications from an on-premise host to cloud-based infrastructure. And, even though they might be dependent on these costly, difficult to maintain legacy applications, the idea of replatforming does require a lot of planning, budget, and resources to do successfully. However, it has become a requirement in order to keep up with innovations like AI.

When evaluating legacy application replatforming, enterprises are often focused on:

• Improving speed to market
• Moving applications to a cloud infrastructure
• Delivering better digital experiences
• Increasing scalability and flexibility
• Supporting compliance and regulatory requirements, especially in industries like financial services

With legacy applications, many organizations run into challenges related to maintenance, support, integration, and user experience. Many outdated systems also struggle to create responsive user experiences that are supported across the latest browsers.

The U.S. Government, for example, still relies heavily on aging infrastructure across many digital services. This might explain why so many of its websites offer an inferior user experience.

Your IT stack defines your business, so your applications should reflect the customer experience that your company hopes to deliver. Updating legacy applications is a business decision, not just an IT decision.

Here’s an overview of legacy systems, legacy software, and the different approaches enterprises can take as they decide to modernize or replatform their current legacy applications.

What is a legacy system?

Legacy systems are outdated technologies that are still being used to run critical day-to-day business operations. They lack IT support and struggle to keep up with an organization’s changing needs.

Most legacy systems were built in the late 1990s or early 2000s and struggle to support modern integrations, scalability, and evolving business requirements.

What is legacy software?

Legacy software refers to outdated applications that continue to function but limit an organization’s ability to scale, innovate, and improve digital experiences. Like legacy systems, legacy software is generally at least 10 years old and cannot easily integrate with new tools, APIs, or cloud infrastructure.

Legacy software modernization is the process of updating or replacing outdated systems, software, and infrastructure to improve performance, scalability, connectivity, and operational efficiency.

Legacy replatforming for brick-and-mortar financial institutions and retailers.

Brick-and-mortar financial institutions, including banks like Wells Fargo, are focused on ensuring that they provide a secure, user-friendly experience on their digital channels. Retailers, especially those that were founded before the digital revolution, are prioritizing building a multichannel e-commerce experience that meets rising customer demands.

Many financial service institutions are knee-deep in rewriting legacy applications built in business languages like COBOL—an object-oriented language built for business use—into languages that require fewer lines of code (like Java) to enhance readability.

As they think about replatforming, retailers and financial institutions should engage in data-driven design thinking to ensure that they are building digital products that meet the needs of their user base.

What are the benefits of legacy application replatforming?

When done correctly, legacy application replatforming can deliver significant business value.

Key benefits include:

• Improved application performance, reliability, and stability
• Stronger protection against data breaches and other security risks
• Better user experiences that improve productivity for both customers and employees
• Greater scalability and flexibility through a more agile IT stack
• Easier integrations with Salesforce and other CRM platforms
• Lower long-term infrastructure costs and a more flexible development process

Replacing legacy applications: Rehosting, replatforming, and other options.

Some legacy applications can be moved to a new environment without too much effort.

But updating outdated technology becomes more difficult when an application is not easily cloud-enabled. In these cases, organizations must either rebuild, replace, or perform another major overhaul to the existing legacy systems.

Today, many enterprises find themselves making a decision as to whether they should replatform or modernize their legacy applications.

Rehosting.

Rehosting — often called “lift and shift” migration — involves moving an application to a new infrastructure without significantly changing the application itself.

While many organizations choose cloud infrastructure, physical and virtual environments are also options for rehosting.

One major advantage of rehosting is that it does not require teams to alter the code or modify key features, so the application’s functionality remains intact.

The focus is on improving workflows, operational management, and processes.

Replatforming.

Replatforming involves migrating an application to a new platform while making targeted code updates to improve compatibility with modern cloud infrastructure.

Legacy application replatforming often requires:

• Minor code modifications
• Updated integrations
• Improved database connectivity
• Cloud optimization
• Application refactoring

This leads to more stability, reliability, and better functionality for operations, users, and other stakeholders. However, the code’s structure remains largely unchanged.

Refactoring.

Replatforming often requires some refactoring, which involves restructuring and optimizing existing code to improve performance and compatibility with modern infrastructure.

While refactoring changes portions of the code itself, the application’s core functionality and user experience typically remain intact.

What if replatforming is not the right solution?

In the past, some applications were client-server based, which meant that they communicated using the end user’s network, not a third-party cloud vendor.

These legacy methods, which are usually not cloud-enabled, have become inefficient, and some applications have failed to comply with new regulations.

Occasionally, an organization has no choice but to completely modernize their applications to fit the latest cloud infrastructure. In these cases, teams may need to rearchitect, rebuild, retire, or replace legacy applications entirely.

Rearchitecting.

Rearchitecting involves modifying an application’s architecture and code so it can support modern infrastructure, integrations, and capabilities.

This process often includes:

• Significant code updates
• Improved scalability
• Modern integrations
• Reduced technical debt

Before beginning a rearchitecting project, teams need to analyze and understand the current architecture and dependencies.

Rebuilding.

Rebuilding means rewriting the application’s current code from scratch while preserving core business functionality.

This approach is often best for:

• Smaller applications
• Systems with severe technical debt
• Applications that cannot scale effectively

Larger enterprise applications may still take years to rebuild, depending on complexity and business requirements. In general, replatforming is a cheaper option than rebuilding your application from scratch or replacing it.

Retiring.

Retiring a legacy application is the process of shutting down or sunsetting obsolete or redundant software. This often occurs as a result of a business trying to consolidate their tech stack. .

The process can involve rebuilding parts of an application, rearchitecting, or even replatforming, depending on the situation.

Replacing.

Replacing a legacy application involves completely removing the original system and implementing a new solution that better supports modern business requirements. Although replacing often delivers the most modern experience, it can also:

• Increase operational risk
• Disrupt internal teams
• Require extensive retraining
• Introduce migration complexity

For many enterprises, replatforming offers a more cost-effective balance between modernization and operational continuity.

No matter the approach, moving your legacy application to the cloud almost always saves money in the long run.

As enterprises approach modern initiatives, many begin with smaller or medium-sized applications, with an eye on growth and scaling up as quickly as possible.

Build a stronger foundation for future digital experiences.

Improving legacy applications is about more than upgrading technology. It’s about creating faster, more flexible digital experiences that can evolve with customer expectations and business needs over time.

Whether your organization is planning a small-scale migration or a larger modernization initiative, having the right visibility into the digital customer or employee experience can help teams make smarter decisions and reduce risk along the way.