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Who Uses Mainframes? How Companies Use The Mainframe

Written by FNTS | May 7, 2026 5:10:56 PM

Think the mainframe is a thing of the past? Think again. Top companies around the globe still count on mainframes for their most important, high-volume tasks. Instead of getting rid of these powerhouse systems, smart organizations are blending them with modern cloud setups to get the best of both worlds in efficiency and security.

For decades, the mainframe has been the mission-critical heartbeat of global enterprises. And despite persistent claims that mainframes belong in the past, the data tells a different story. According to Forrester’s State Of Mainframe Global 2025 report, more than half of organizations currently using mainframes expect to increase their mainframe usage over the next two years.

The misconception that mainframes are obsolete typically stems from one false assumption: that modern IT requires abandoning legacy systems entirely. In reality, 45 of the world’s top 50 banks, 67% of Fortune 100 companies, and 7 of the top 10 global retailers still rely on mainframes to run their most complex and critical operations. These organizations aren’t clinging to the past; they’re building forward.

Instead of replacing systems that continue to deliver unmatched reliability and security, forward-thinking enterprises are modernizing their mainframes and evolving how they operate while preserving what works. The industry momentum for this approach has never been stronger in 2026.

What Is Mainframe Modernization?

Mainframe modernization is the process of updating how mainframe systems are deployed, accessed, and integrated, without completely replacing them. The goal is to evolve the infrastructure to support modern digital demands while maintaining core system stability.

Today’s mainframes are modern technology, featuring the fastest chip speeds, dedicated AI inference engines, pervasive encryption, and native support for contemporary programming languages.

What they often lack is the modernized management layer that helps organizations maximize their value in a hybrid world.

To bridge this gap, modernizing a mainframe environment typically includes:

  • Integrating mainframes with cloud platforms using APIs.
  • Transitioning infrastructure management to Mainframe-as-a-Service (MFaaS).
  • Modernizing application architectures for better interoperability.
  • Expanding data accessibility for analytics, AI, and automation tools.
  • Transitioning from green screen interfaces to modern, user-friendly experiences.

Mainframe modernization is treated as an evolutionary strategy, one that lets organizations move at their own pace while maintaining full control over the systems their business depends on.

 

Want a deeper look at why enterprises continue investing in mainframes? Download our white paper to explore how organizations are modernizing mission-critical infrastructures.

 

Who Uses Mainframes and What Are the Mainframe Advantages?

The organizations who use mainframes today include global banks, healthcare institutions, government agencies, and major retailers. The primary mainframe advantages are unmatched reliability, high-volume transactional performance, and proven hardware-level security.

To understand why companies using mainframes remain committed to the technology, it helps to look at what these systems actually do, and how difficult they would be to replace. These industries rely on mainframes for high-volume transaction processing, data integrity, regulatory compliance, and continuous availability. These are requirements that few other platforms can match at scale.

The core advantages that keep mainframes in the picture include:

  • Unmatched reliability: Mainframes are engineered for continuous uptime, delivering the kind of always-on availability that mission-critical operations demand.
  • Proven security: With pervasive hardware-level encryption, mainframes offer data protection capabilities not commonly found on other platforms.
  • High-volume workload performance: Mainframes consistently outperform other platforms in accessing and processing massive volumes of transactional data.
  • Hybrid-ready architecture: Rather than operating in isolation, today’s mainframes are increasingly integrated into hybrid cloud environments, extending their value across the enterprise.

The question organizations are asking is no longer “should we replace the mainframe?” It’s “how do we optimize it within a modern hybrid architecture?” The narrative, as Forrester confirms, has decisively shifted from migration to optimization.

The Benefits of Modernizing Mainframe Systems

When organizations invest in mainframe modernization, they unlock new value from systems that already carry decades of institutional knowledge, without the cost or risk of rebuilding from scratch. Modernization enhances agility, reduces technical debt, and enables seamless AI integration.

Greater Agility and Speed to Innovation

Removing barriers between legacy systems and modern platforms lets development teams build, deploy, and scale new capabilities faster. Adopting DevOps methodologies alongside mainframe operations, for example, can dramatically improve release cycles and responsiveness to business needs.

Long-Term Cost Optimization

Maintaining a legacy-only environment can become one of an organization’s fastest-growing IT expenses, particularly as technical debt accumulates. Adopting a Mainframe-as-a-Service (MFaaS) model helps organizations eliminate ongoing capital burdens through a lift-and-shift migration, reducing annual expenses by 15–20% while delivering around-the-clock support.

Seamless Integration with AI and Modern Technologies

Modernized mainframes integrate naturally with AI tools, automation platforms, and analytics applications. Businesses are now leveraging advanced AI capabilities, including AIOps for predictive analytics and AI-enabled workflows, directly within mainframe environments. The result is improved uptime, faster incident resolution, and more intelligent resource allocation.

Improved Data Accessibility and User Experience

APIs and hybrid architectures make it easier for development teams and business users alike to access and act on mainframe data across the organization, transparently and in real time, without requiring deep knowledge of where or how that data is sourced.

Comparing Infrastructure: IaaS Pros and Cons vs. MFaaS

When evaluating infrastructure upgrades, IT leaders must carefully weigh IaaS pros and cons against specialized solutions like MFaaS. While Infrastructure-as-a-Service (IaaS) offers broad cloud flexibility, Mainframe-as-a-Service (MFaaS) is specifically tailored to the unique architectural needs of legacy systems.

The pros of standard IaaS include rapid scalability and a vast ecosystem of third-party integrations, making it ideal for distributed applications. However, the cons of IaaS often involve a lack of native support for legacy mainframe protocols and potential security gaps when handling highly sensitive, high-volume transactional data.

In contrast, MFaaS provides a cloud-like consumption model specifically designed for mainframe workloads. MFaaS is better suited for teams that need to maintain strict regulatory compliance and absolute data integrity, while standard IaaS works best when launching net-new, cloud-native applications.


Resource: Access our 2026 ISG Provider Lens® Reports to learn why FNTS was named a Leader in Mainframe-as-a-Service (MFaaS) for the U.S. and U.S. Public Sector markets.


Common Mainframe Modernization Approaches

There is no single modernization path that fits every organization. The right approach depends on the complexity of existing systems, business priorities, and long-term infrastructure goals.

Industry leaders typically support organizations across several major modernization strategies:

  • Rehost: Move workloads to a cloud-like mainframe infrastructure via MFaaS without changing application code. This approach reduces capital burden and delivers immediate cost savings.
  • Refactor: Use generative AI and automation to analyze existing code, remove obsolete components, and optimize performance and CPU utilization, without a full rewrite.
  • Replatform: Connect applications to multicloud or hybrid environments, enabling seamless interoperability between the mainframe and modern infrastructure.
  • Hybrid approaches: Combine the stability of legacy systems with the flexibility of modern cloud infrastructure, preserving what works while expanding what’s possible.

Challenges to Consider in Modernization

Mainframe modernization offers significant upside, but it requires thoughtful planning to navigate complex code dependencies and the industry-wide mainframe talent gap. Protecting uptime and data integrity during the transition is critical.

Organizations should prepare for:

  • Complex dependencies: Legacy systems often house decades of interconnected business logic that must be carefully assessed before any migration or refactoring effort.
  • Workforce specialization: Mainframe expertise is increasingly rare as senior professionals retire. Organizations must find ways to bridge that talent gap without disrupting operations.
  • Transition risk: Protecting uptime and data integrity during any infrastructure change is non-negotiable. Modernization must be approached with a clear risk management framework.
  • Budget and timeline alignment: Modernization is a long-term investment. Aligning priorities with broader IT and business goals is essential for sustainable progress.

To address the talent gap at its source, the industry is increasingly taking proactive measures. Partnerships with academic institutions, such as the mainframe curriculum launched at the University of Nebraska at Omaha's College of Information Science and Technology, are helping to create a pipeline of trained professionals ready to carry the mainframe legacy forward.

The Evolving Role of Mainframes in 2026

Mainframes are far from relics of the past; they remain the foundation of mission-critical operations for the world’s most complex organizations. In 2026, companies using mainframes are not standing still. Instead, they are actively modernizing, optimizing, and integrating their legacy systems into cutting-edge hybrid architectures.

Find an IT Partner to Unlock Your Mainframe’s Full Potential

By leveraging approaches like MFaaS, API-driven interoperability, and AI-enabled AIOps, you can preserve the unmatched security of the mainframe while gaining the agility needed to compete in a digital-first world. Partnering with an expert can help you navigate this journey and unlock the full potential of your legacy systems.