What Is Application Modernization? 

Application modernization involves updating or transforming legacy software systems to enhance their capabilities. This typically includes implementing newer technologies, methodologies, or architectural patterns to improve the system’s performance and functionality. It can help organizations keep pace with changing requirements and technological advancements without entirely replacing their existing systems.

The goal of application modernization is to extract more value from the legacy investment by enabling integration with modern systems and ensuring the software continues to meet the current and future needs of the business. This ensures operational continuity, improves user experiences, and enhances overall business agility.

What Are the Benefits of App Modernization? 

By modernizing applications, companies can benefit from the following:

  • Accelerated innovation and time to market: Newer technologies like artificial intelligence and data analytics can accelerate product iterations, reduce the time needed to enhance features, and expedite time to market. 
  • Compatibility and agility: Updating the underlying technology stack to newer, more flexible platforms like cloud computing, allows for better integration with other modern applications and systems. Improved compatibility simplifies IT management and reduces operational overhead by enabling seamless interactions and data flow between systems.
  • Security and reliability: Developers can integrate advanced security protocols and tools, which are often updated more frequently than older systems, reducing vulnerability to cyber threats. The shift towards structures like microservices and managed services also decentralizes data processing, further enhancing security.

Application Modernization vs. Infrastructure Modernization 

Application modernization focuses on updating the software elements of a system to improve functionality and performance. It often encompasses rearchitecting apps, refining code, and sometimes moving applications to new runtime environments.

Infrastructure modernization involves refreshing the underlying hardware and network systems that support software applications. This can include moving to newer servers, adopting cloud services, or implementing virtualization technologies. While application modernization can be undertaken independently, it often goes hand-in-hand with infrastructure upgrades to maximize operational efficiency.

Learn more in our detailed guide to IT infrastructure modernization (coming soon)

Patterns for Modernizing Applications (the 7 Rs)

There are several approaches that can be used to modernize an application.


Replacing an application means substituting the old system with a new one that better meets current operational needs. This approach is usually considered when the existing system’s maintenance costs outweigh those for a new system, or when the technology is obsolete. However, it’s a considerable investment and involves risks like extended downtime and data migration challenges.


Retaining involves keeping the existing application with minor updates or changes. This is viable when the application meets business needs and doesn’t require extensive modifications. Retention is cost-effective and involves low risk, but may limit the ability to integrate with modern systems and technologies.


Retiring obsolete applications involves phasing out non-essential systems. This frees up resources from maintaining systems that no longer provide valuable service or functionality. The process typically involves identifying and eliminating applications based on redundancy, low usage, or unjustified maintenance costs. Retiring applications can lead to short-term disruptions.


Rehosting, often referred to as “lift and shift,” involves moving an application from one environment to another without redesigning the application. This method is common for relocating to cloud environments to benefit from reduced infrastructure costs and enhanced scalability. Though rehosting can be executed quickly and at a relatively low cost, the performance boost may be limited if applications are not optimized for the new environment.


Replatforming involves making moderate changes to the app’s code to fit a new platform without altering its core functions and features. This includes optimizations that leverage the new platform’s capabilities without a major code overhaul. Replatforming strikes a balance between cost, risk, and benefit, making it an attractive option for those not ready for a full rebuild.


Rewriting an application involves complete re-engineering, using modern technologies and platforms. This approach is adopted when the existing system can no longer meet functionality, performance, or scalability requirements even with extensive modifications. It requires substantial investment and carries a high level of project risk.


Refactoring entails restructuring and optimizing existing code without changing its external behavior. It focuses on improving nonfunctional attributes such as the efficiency, maintainability, and scalability of software. Refactoring is essential for legacy applications that need improvements within current architectural frameworks.

Important Technologies for Application Modernization 

Here are some of the main technologies that organizations leverage when modernizing their applications.

Cloud Computing

Cloud providers offer resources such as servers, storage, and databases over the Internet. By moving applications to the cloud, businesses can avoid the high costs of maintaining physical infrastructure and achieve better disaster recovery. Cloud services make advanced technologies more accessible, enabling optimization and supporting remote access and collaboration.

Containers and Kubernetes

Containers provide a lightweight method for packaging and running applications independently from the underlying infrastructure. Kubernetes, an open-source container orchestration system, enhances containers’ management, allowing for automated deployment, scaling, and operations of application containers across clusters of hosts. Containerization supports a microservices architecture, improving scalability and fault isolation. 


Microservices architecture breaks down applications into smaller, autonomous services. This separation allows independent development, scaling, and failure management of different application components. Microservices are well-suited for dynamic environments like the cloud, enabling quicker updates and improving service delivery. This approach helps avoid large-scale system failures, as issues in one service can be handled without affecting others.

AI and Machine Learning

AI and machine learning technologies enable features such as predictive analytics, automated decision-making, and personalized user experiences. By embedding AI capabilities, applications can process large volumes of data, gain insights, and respond in real-time. These technologies also help in optimizing operations and can predict user behavior and system failures.

Key Challenges of Application Modernization

While modernizing applications if often necessary, organizations may experience some challenges during the modernization process.

Complex Legacy Applications

Legacy systems are usually large, monolithic, and intertwined with business operations, making any changes risky and complex. Their outdated architectures and codebases can make integration with new technologies more challenging. Modernizing these applications requires careful planning and execution to ensure business continuity. 

Learn more in our detailed guide to legacy system modernization (coming soon)

Technical Debt

Technical debt refers to the implied cost of additional rework caused by choosing an easy solution now instead of using a better approach that would take longer. Technical debt can accumulate over time, resulting in increased maintenance costs. Addressing technical debt often means refactoring the code or rewriting the application entirely.

Skill Gaps

As new technologies emerge, organizations often find that their current IT staff do not have the necessary skills to implement modern solutions. Recruiting new talent or training existing employees can become a hurdle. Organizations need to invest in continuous education and technology training programs to keep their team updated with the latest developments.

Budget Constraints

Often, organizations need to balance the cost of upgrading their systems with the projected ROI. Tight budgets mean that companies must prioritize modernizing the most critical aspects of their IT infrastructure. Organizations should look for incremental modernization strategies that offer the highest impact at the lowest cost, prioritizing and staging upgrades. 

Transforming Legacy Applications: 5 Tips for Success 

Here are some of the measures that organizations can take to improve their application modernization processes.

1. Ensure Thorough Assessment and Planning

Before launching the modernization process, conduct a comprehensive assessment of your existing applications. This involves identifying the applications that need modernization, understanding their current architecture, and evaluating their business impact. 

Involve stakeholders from different departments to gather information about the system’s functionality and performance issues. Tools like application performance management (APM) can help in assessing the current state and identifying bottlenecks or inefficiencies.

Next, develop a detailed roadmap that outlines the modernization strategy, including timelines, resources, and milestones. Prioritize applications based on their business value and complexity. A well-defined plan should also include risk assessment and mitigation strategies to address potential challenges that may arise during the modernization process. 

2. Use an Incremental Modernization Approach 

Instead of attempting a complete overhaul in one go, adopt an incremental modernization approach. This involves gradually updating and improving components of the application. Start with the least critical parts and learn from the initial efforts. This staged approach minimizes disruptions to business operations and allows for continuous feedback and adjustment.

Breaking down the modernization process into smaller, manageable tasks can help in maintaining control and reducing risks. Start by refactoring one module before moving on to rehosting or replatforming another part of the application. 

3. Adopt DevOps Practices

DevOps emphasizes automation, continuous integration, continuous delivery (CI/CD), and close collaboration between development and operations teams. Automating the deployment pipeline reduces manual errors and speeds up the release cycle, allowing for faster iterations and more reliable deployments.

Incorporating DevOps also facilitates better monitoring and feedback mechanisms. Using tools like Jenkins for CI/CD, Docker for containerization, and Kubernetes for orchestration helps streamline the modernization process. 

4. Focus on Security and Compliance

Security should be a top priority during the modernization process. As applications are updated or moved to new environments, implement security measures to protect sensitive data and ensure compliance with regulatory standards. Conduct regular security assessments and audits to identify vulnerabilities and address them promptly.

Adopt security best practices such as integrating security testing into the CI/CD pipeline, using encryption for data at rest and in transit, and implementing access controls based on the principle of least privilege. Consider also compliance with standards such as GDPR, HIPAA, or PCI-DSS, putting policies and procedures in place to ensure that the application adheres to them.

5. Implement a Change Management Strategy

Establish a comprehensive change management strategy that includes clear communication, training, and support plans. Communicate the benefits and objectives of the modernization effort to all stakeholders to ensure buy-in and reduce resistance.

Training is essential to equip employees with the necessary skills to operate and maintain the modernized systems. Provide ongoing support and resources to help them transition smoothly. Establish a feedback loop to gather insights from users and make necessary adjustments. This strategy helps manage the human aspect of modernization.

Related content: Read our guide to application modernization strategy (coming soon)

Documenting Legacy Code with Swimm

Legacy code represents a significant challenge as well as an opportunity for software organizations. Managing legacy code entails more than just dealing with untidy or outdated code; it involves transforming it into a reliable and efficient foundation that supports future development initiatives. Handling legacy code effectively can lead to considerable long-term savings and heightened productivity, marking it as a strategic priority for any R&D organization. 

Swimm helps you and your team document legacy code in an easy, manageable, and effective way. Utilize AI to create docs about legacy code and then discover those docs directly in your IDE. Those docs then stay up to date with ongoing code changes, boosting your team’s productivity and enhancing the quality of your codebase. 

Learn more about modernizing legacy code with Swimm