In today’s fast-paced digital world, businesses must continuously evolve their application landscape to stay competitive. Legacy applications, those built on outdated technologies, often become bottlenecks for innovation, efficiency, and security. But modernizing these applications isn’t just about keeping up with the latest trends—it’s about ensuring long-term business success. To better understand the modernization process, the challenges involved, and the best practices for a successful transformation, we sat down with our experienced full-stack developer Tero, who has spent years modernizing legacy systems with newer programming languages and frameworks.

What’s a typical process when a legacy application gets modernized?

Tero: The typical process for modernizing a legacy application starts with mapping out the existing technologies, integrations, and architecture. We evaluate which technologies can be upgraded to newer versions and which need to be completely replaced. This assessment may involve prototyping and proof-of-concept phases.

Once the modernization plan is finalized—taking into account both business and technical requirements—the application undergoes redevelopment or refactoring. After thorough testing, quality assurance, and necessary certifications, the data is migrated, and the modernized application is deployed into production.

What are the challenges to be expected?

Tero: There are both technical and non-technical challenges. One of the biggest non-technical challenges is alignment—since the application has existed for years, different stakeholders may have conflicting ideas about its priorities and importance. Some might resist change, fearing disruption or cost overruns.

From a technical standpoint, challenges arise when the application contains undocumented features or dependencies that no one in the organization fully understands. Sometimes, critical functionality is implemented outside the main application as scripts or database procedures, making migration complex.

Another common issue is version incompatibility. Legacy dependencies might not be certified to work with the latest version of the technology stack, yet continuing to use outdated platforms—such as a 10-year-old version of Java or Node.js—is not an option. These unforeseen incompatibilities can surface during development, in build and deployment pipelines, or even in the runtime environment.

What kind of team is ideal for these projects?

Tero: The ideal team for a modernization project is lean but cross-functional. It should be small enough to stay agile but should have all the necessary expertise to implement features independently without relying on external teams.

The team should include:

• Developers skilled in both legacy and modern technologies.
• DevOps engineers to handle build pipelines and deployment automation.
• Business analysts who understand the application’s purpose and requirements.
• UX/UI designers to enhance usability if necessary.
• Quality assurance and testing professionals to ensure a smooth transition.

Having a domain expert within the team is also beneficial, as they can validate business logic and help avoid unnecessary development cycles.

What’s needed so that the team can deliver what the business wants?

Tero: First and foremost, businesses must recognize that modernization is a strategic initiative, not just a technical upgrade. Keeping applications up to date continuously prevents costly, large-scale modernization projects in the future.

For a successful modernization:

• Plan for long-term maintenance so that applications don’t fall into obsolescence again.
• Allocate time for prototyping and experimenting with new technologies.
• Ensure clear and continuous communication between business and technical teams.
• Allow for some flexibility—modernization can reveal unexpected challenges that require agile problem-solving.

Final Thoughts: The Business Benefits of Modernization

Modernizing legacy applications brings tangible business benefits, such as:

• Increased agility – Faster deployment of new features and capabilities.
• Enhanced security – Protection against vulnerabilities that exist in outdated systems.
• Improved performance – Optimized applications run faster and more efficiently.
• Cost efficiency – Reduced maintenance costs and lower technical debt.
• Better user experience – Modern interfaces and improved accessibility for employees and customers.

On the flip side, failing to modernize can lead to security risks, rising maintenance costs, and missed opportunities for innovation. Businesses that proactively manage their application landscape will always have the competitive edge.

If your company is still running critical applications on outdated technologies, now is the time to consider modernization. The process may be complex, but with the right team, strategy, and approach, it can be a game-changer for your business.