Your legacy mainframe is likely vital to business operations, but might not be as open to innovation and new technologies as you’d like. That’s where mainframe modernization comes in, and we’re going to tell you everything you need to know about it.
What is mainframe application modernization?
Mainframe modernization is when you update your old legacy mainframe system to meet the challenges posed by new technology and grasp the opportunities of digital transformation. It can involve migrating essential applications and data to the cloud or may mean adapting a hybrid model (where both legacy systems and the cloud co-exist).
Mainframe modernization has become a higher priority across various industries in recent years. It can help varied companies achieve their business goals and initiatives, improve customer experience and device management, and take advantage of newer technologies, such as artificial intelligence.
It often involves both application development and the use of microservices.
Mainframe migration is a closely related phrase. It’s one particular way to modernize the system and is when you migrate some or all of your business mainframe applications and data to the cloud. With increasingly high generation and use of data, cloud-based computing can offer organizations better functionality, as well as the ability to access data and systems from anywhere in the world.
Why does legacy mainframe modernization matter?
If your legacy mainframe has had a long lifecycle and is outdated, mainframe modernization is how you adapt it to better cope with modern demands and new technologies.
There are numerous reasons why you should modernize your mainframe, from reducing costs to improving workflows and performance. It also means you can become cloud-native, and adapt more quickly to future changes in the market and new tech. We’ll get more deeply into the benefits of mainframe legacy modernization a little later.
Mainframe modernization techniques and approaches
Many legacy systems are powered by COBOL or other older programming languages. That means you need to look at how to make them work with newer applications and languages such as Java. You must also consider the increasing use of AI and machine learning and how they fit within your business model.
Choosing the right modernization approach depends on your organization’s needs, risk tolerance, and long-term digital strategy. Here are three of the most common approaches—and how OpenLegacy supports each one:
Modernize in place
Modernizing in place allows organizations to retain their core legacy systems while enhancing them with modern capabilities. It’s a cost-effective, low-risk strategy that provides immediate improvements in agility and integration.
OpenLegacy plays a key role by exposing legacy business logic as modern, secure APIs—unlocking core system functionality without invasive code changes. This allows companies to connect legacy systems directly to cloud-native applications and services, enabling continuous innovation with minimal disruption.
Rehost/re-platform
This approach involves migrating workloads to a new environment—such as the cloud or a distributed infrastructure—while retaining core business logic and workflows.
OpenLegacy supports this phased, hybrid model by generating integration-ready APIs that allow legacy and cloud environments to operate in parallel. This enables gradual migration, reduces risk, and ensures legacy capabilities remain accessible during and after the transition.
Replace/rewrite
Replacing or rewriting your legacy systems from the ground up is the most comprehensive—but also the most resource-intensive—modernization strategy. It often involves completely decommissioning the mainframe and rebuilding business processes in a new, cloud-native architecture.
Even in full-replacement scenarios, OpenLegacy accelerates success by serving as a transitional integration layer. Our platform helps organizations extract critical logic and data from legacy systems and expose it in modern formats—ensuring continuity during redevelopment, reducing risk, and streamlining the path to full modernization.
Benefits of mainframe modernization
Organizations are often hesitant to modernize legacy mainframe systems due to concerns about cost, data loss, or operational disruption. These concerns are valid, but the potential benefits far outweigh the risks when approached strategically.
Here are some of the top advantages modernization can bring:
1. System modernization
Your legacy systems built on COBOL, PL/I, Assembler, and other older languages can struggle to support modern workloads.
By leveraging modern APIs, your DevOps team can integrate existing applications into more modern (and distributed) cloud-native services—enhancing functionality, agility, and long-term innovation potential.
2. Integration with the cloud
You’re probably generating and using more data than ever. In fact, the amount of data generated, captured, copied, and consumed worldwide is growing rapidly, and that growth is predicted to continue apace:
Modernizing your mainframe enables seamless integration with cloud architecture. That means you can scale storage, support virtualization, and unlock hybrid capabilities that combine the strengths of legacy systems with cloud flexibility.
3. Reduced costs
Legacy systems are notoriously expensive to maintain. Licensing, infrastructure, and labor costs increase as workloads grow. Modernization allows you to reduce these expenses through better resource distribution, smarter integration strategies, and AI-powered automation—delivering both immediate and long-term savings.
Common mainframe modernization challenges
Despite the benefits, modernization comes with its own set of challenges. Understanding them upfront allows for better planning and risk mitigation.
Skills gaps in your organization
You might be wary of mainframe modernization if you feel it will also require significant changes to your workforce. Perhaps, for example, your team lacks the expertise to operate or maintain a new system. You might have to hire new staff or retrain existing ones, which can be expensive.
The other potential cost savings of modernization, however, can offset this. What’s more, as time passes, it’s increasingly the expertise to operate and manage older, legacy systems that’s in shorter supply than that related to more modern alternatives.
Complexity of legacy systems
Over years or decades, legacy systems accumulate customizations, patches, and workarounds that make them complex and fragile. While modernization can be daunting, moving toward an open, modular architecture is ultimately more sustainable and adaptable.
Downtime and business disruptions
Mainframes often support mission-critical operations, so the risk of disruption during modernization is a valid concern. However, platforms like OpenLegacy enable phased, low-risk transitions—keeping systems running while modernization progresses behind the scenes.
Compliance and data protection
Enterprises—especially those in industries such as healthcare and financial services—rightly view compliance and data protection as vitally important. Any process that involves updating systems or moving data held within can pose potential risks in this area. It’s crucial, therefore, that cybersecurity and the protection of sensitive data is a cornerstone of any mainframe migration strategy.
What to consider to ensure a successful mainframe modernization strategy
Modernizing a mainframe isn’t just about technology—it’s about aligning strategy, people, and processes. Here’s what to keep top of mind:
1. Stakeholder alignment
Modernization should serve business goals, not just IT aspirations. Align all stakeholders early to define shared objectives, KPIs, and success criteria that bridge both business and technology outcomes.
2. Embrace a change-ready culture
Modernization requires more than tools—it demands cultural buy-in. Encourage openness to cloud-native tools and agile workflows, and ensure that legacy capabilities are not lost in the process.
3. Set clear goals & methods
Start with the end in mind. Define whether your path includes full migration, a hybrid model, or staged integration—and choose methods and tools that support that vision with minimal disruption.
4. Involve the right people
Successful modernization relies on the right mix of internal champions and external partners. Many organizations turn to experienced vendors for expertise in integration, automation, and best practices.
OpenLegacy offers the platform and experience to reduce risk and accelerate outcomes—leveraging well-documented, structured methodologies that replace fragile, manual processes.
5. Learn from others
Look to similar organizations that have modernized successfully. Case studies and shared learnings can offer valuable insights, flag potential pitfalls, and help shape your roadmap with proven strategies.
How OpenLegacy can help with mainframe modernization
Mainframe modernization is a complex journey, but it doesn’t have to be a risky one.
OpenLegacy provides a platform built specifically for structured, secure, and scalable modernization. Our automation-first approach allows you to analyze your existing systems, plan integration points with clarity, and execute transformation with AI-ready APIs—reducing risk at every step.
From legacy system visibility to cloud deployment, OpenLegacy helps you modernize with confidence—keeping critical systems running while you move toward a future-ready architecture.
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