Why mainframes still matter in a cloud-first world

In today’s technology driven landscape, some of the most impactful systems continue to function reliably behind the scenes, driving critical operations without fanfare. They don’t show up in headlines or keynote speeches. But they’re everywhere, handling payments, running government services, booking flights, and keeping the digital world ticking. We’re talking about mainframes.

Mainframes might seem like something from the past, but they continue to play a critical role. Upon closer examination, it becomes clear they’re still vital, and evolving in ways that might surprise you.

The tech you don’t notice (but likely use daily)

When most people picture a mainframe, they think of a massive machine tucked away in some forgotten room. Something from another era. But that’s not the reality. Mainframes are still at the heart of many critical operations across industries.

Think about your last online purchase. Or the last time you transferred money to a friend. Booked a flight. Those actions rely on mainframe systems operating behind the scenes. These systems are built to process massive amounts of data quickly and securely, and they still dominate in sectors where failure is not an option—like banking, healthcare, government, and aviation.

One conversation-stopping stat? Around 67% of Fortune 500 companies rely on mainframes. And it gets even more serious with banks—90% of them still use mainframes for core operations. That’s not about legacy—it’s about reliability, integrity, and performance.

Still growing, still adapting

You’d think with the widespread usage of cloud technologies, mainframe use would be shrinking. But the opposite is happening. Organizations are actually planning to store more data on them. And these systems aren’t just being maintained—they’re being upgraded.

Modern mainframes use cutting-edge processors and top-tier storage. They’re not stuck in the past. And they’re not just hardware, either. Software on mainframes has come a long way. Virtualization, containers, and open source tools are now part of the package. Even generative AI is starting to run on these machines.

Usage has jumped by 350% over the past decade, measured by how much work they’re doing. That’s not slow decline—that’s growth.

Making mainframes more accessible

One of the old challenges with mainframes was the specialized skill set they required. But that’s changing too. Today, they support Linux, containers, and cloud-native tools. That makes them a lot more approachable for newer developers who don’t have a traditional mainframe background.

This shift is opening up mainframes to a broader pool of talent. With the evolution of mainframe software that now supports modern IDEs and DevOps workflows, developers can use familiar tools while working with a platform that’s rock-solid and proven.

Mainframes and the cloud: Better together

For a long time, people saw mainframes and cloud as competing forces. One would eventually replace the other. But that is outdated thinking. The future isn’t one or the other—it’s both.

This is where hybrid IT comes in. Mainframes now work smoothly with cloud environments. They’re designed to connect through APIs and microservices, which means companies can keep their reliable core systems while layering on new features and experiences through the cloud.

It’s not about ripping out and replacing. It’s about building on what already works.

On-demand power

Even how companies access mainframes is changing. You don’t have to buy and maintain your own machine anymore. Services like IBM Z-as-a-Service let businesses tap into mainframe resources on demand, like they would with any other cloud platform.

With Kubernetes, they can even move workloads between the cloud and the mainframe depending on what makes the most sense. That kind of flexibility is something a lot of organizations are looking for.

Security that’s built in, not bolted on

If there’s one area where mainframes have always led, it’s security. These systems were designed to handle sensitive data and mission-critical transactions from the ground up.

They feature built-in protections like pervasive encryption, which keeps data scrambled whether it’s stored or moving. That makes it nearly impossible for unauthorized users to make sense of anything, even if they get in.

Mainframes also offer insane levels of reliability. Some reach what’s called “five nines” of uptime—that’s 99.999% availability. In practical terms, it means less than six minutes of unplanned downtime in an entire year.

The real-world roadblocks

Although it is not a perfect system. There are some definite bumps in the road when it comes to getting mainframes and cloud systems to play nicely together. For a lot of companies, the idea of moving core systems off a mainframe is just too risky. We’re talking about applications that have been around for decades—unpacking all that legacy code isn’t quick or simple.

Then there’s regulation. In sectors like finance or government, you can’t always just throw everything into the public cloud and call it a day. There are strict rules about where data lives, how it’s handled, and who can access it.

And let’s not forget the skills gap. You’ve got seasoned mainframe experts on one side, some of them close to retirement. On the other side, you’ve got a younger crowd that knows cloud and modern stacks but hasn’t touched a mainframe. Bridging that gap is no small task.

Still central to the big picture

Even with the challenges, mainframes aren’t going anywhere anytime soon. Most experts say they’ll stay essential for the next five years at least. And it’s not just about keeping them around—it’s about doing more with them.

There’s a growing push to squeeze even better performance out of these systems. That might mean tuning how data is sorted, streamlining databases, or speeding up certain processes. The goal isn’t just to keep the lights on—it’s to make mainframes a real part of modern infrastructure.

62% of execs and IT professionals expect mainframes to handle more workloads moving forward, not fewer. That says a lot about where things are headed.

Quiet strength, lasting impact

Take a step back, and the story of the mainframe is one of quiet resilience. It’s easy to get caught up in whatever’s new and flashy. But sometimes, the tech that just works—the systems that deliver day after day without drama—those are the ones holding everything together.

Mainframes may not be the stars of the show, but they’re still running the engine room. And as they keep adapting—connecting to cloud tools, supporting AI, scaling flexibly—they’re proving that legacy doesn’t mean outdated. It just means built to last.