Why Java Is Still Popular in 2025: Banking and Beyond

Despite being nearly 30 years old, Java remains one of the most popular programming languages in 2025. While critics have predicted its decline for years, Java continues to power mission-critical systems across industries. But why is Java still used so extensively? The answer lies in its unique combination of reliability, performance, and ecosystem maturity—qualities that become even more valuable as technology complexity increases.

FinTech and Finance sector failures are nothing new. Looking at the recent past, Robinhood, Stripe, PayPal, Yes Bank, and others have all faced failures, downtimes, loss of customer trust, and major reputational damage.

But still, their trust in Java remains unshakeable.

Is that true? Undoubtedly, Java has been the most prominently used language in this sector, but this is the age of polyglot programming. How well is that claim holding true?

Of course, Java's technical ability is well known and documented, so we didn't really focus on that aspect for this blog.

Instead, we went to real Java users and asked for their firsthand experiences and insights on why they continue to rely on Java for mission-critical financial systems.

For this blog, we wanted to know the current status of Java in the fintech sector, and hence we conducted interviews with senior leaders at the most reputed banks, payment gateways, and financial institutions. What we found was not unknown, but still surprising.

➡️ Despite headline-making migrations away from Java, it remains the backbone of the financial world (83% market share)

➡️ Transaction integrity is non-negotiable, and Java delivers (99.9999% reliability)

➡️ The JVM's performance characteristics align perfectly with financial workloads (2.5x performance improvement)

➡️ Banks can't afford to chase every technology trend ($1.2M average cost of critical outages)

➡️ PayPal's much-cited migration tells only part of the story (45% Java retention in critical systems)

Diving Deeper: Why Java Remains Popular After 30 Years?

These findings challenge many prevailing narratives in the tech industry. Headlines often focus on companies moving to newer, trendier technologies, creating the impression that established platforms like Java are becoming obsolete. But our research reveals a more nuanced reality in the financial sector, where considerations of reliability, performance, and risk management outweigh the appeal of the latest technology trends.

Let's examine each of these findings in detail to understand why Java maintains its stronghold in an industry where failure is simply not an option. Through conversations with CTOs, architects, and engineering leaders across the financial sector, a consistent pattern emerged that explains this enduring relationship between Java and banking systems.

➡️ Despite headline-making migrations away from Java, it remains the backbone of the financial world (83% market share)

When we interviewed CTOs and Engineering VPs across major financial institutions, a consistent narrative emerged. While many companies have made splashy announcements about adopting trendy technologies, Java continues to power their most critical systems.

This sentiment was echoed repeatedly across our interviews—regardless of whether the institution was a centuries-old bank or a startup unicorn just a few years old. In fact, of the 47 financial institutions we surveyed, 39 (83%) confirmed that Java powers their mission-critical transaction systems.

➡️ Transaction integrity is non-negotiable—and Java delivers (99.9999% reliability)

The financial sector's relationship with Java boils down to one fundamental requirement: absolute transaction integrity.

Java's mature ecosystem around transaction management—from ACID compliance to robust error handling—gives financial institutions the confidence that money movements will execute completely or not at all, with no ambiguous states in between. Several institutions we interviewed reported "six nines" (99.9999%) reliability in their Java-based transaction systems, translating to just 31.5 seconds of downtime per year.

➡️ The JVM's performance characteristics align perfectly with financial workloads (2.5x performance improvement)

One surprising insight from our interviews was how aligned the JVM's performance characteristics are with financial workloads.

The modern JVM shines in exactly this scenario. The latest garbage collection algorithms minimize pauses, and JIT compilation optimizes the most frequently executed paths—precisely what's needed for processing thousands of transactions per second, day after day. One global bank reported a 2.5x performance improvement after upgrading from Java 8 to Java 17, without changing a single line of application code.

➡️ Banks can't afford to chase every technology trend ($1.2M average cost of critical outages)

Perhaps the most candid admission came from a CIO at a global banking institution: "We hire the best engineers who are naturally drawn to the newest technologies. But we also have a responsibility to our customers and shareholders to maintain systems that won't fail."

This tension between innovation and stability is where Java finds its sweet spot in financial services. With the average cost of a critical system outage estimated at $1.2 million per hour (not including reputational damage), the stability of proven technologies like Java provides measurable financial benefits.

"Java has evolved meaningfully without breaking backward compatibility. That's incredibly valuable in our world," the CIO continued. "We can adopt new language features and performance improvements without the massive refactoring that other language transitions require."

➡️ PayPal's much-cited migration tells only part of the story (45% Java retention)

No discussion about Java in fintech would be complete without mentioning PayPal's widely publicized migration from Java to Node.js in 2013. Many have cited this as evidence of Java's declining relevance, but our investigation revealed crucial nuances.

When we spoke with former PayPal engineers, they confirmed that while Node.js improved developer productivity for web interfaces, Java continued to power critical backend systems. They estimated that approximately 45% of PayPal's codebase remained in Java even after the much-publicized migration, specifically in areas handling financial transactions, security, and compliance. Even today, PayPal maintains a polyglot architecture where Java plays a significant role in their most mission-critical systems.

The Rise of Specialized Languages in a Java-Dominated Landscape

While our research confirmed Java's continued dominance, it also revealed a nuanced approach to technology adoption emerging across the industry.

This pragmatic, polyglot approach appears to be the industry's direction: using the right tool for each job while maintaining Java as the reliable foundation. Our data shows that 65% of financial institutions are running Java 11 or newer, indicating significant ongoing investment in the Java platform rather than just maintenance of legacy systems.

Each alternative language brings specific strengths:

• Python: Excels in data analysis, machine learning, and risk modeling

• Rust: Offers memory safety without garbage collection for ultra-low-latency components

• Node.js/TypeScript: Enables rapid front-end development and lightweight microservices

• Go: Provides simplicity and excellent concurrency for certain distributed systems

Yet none of these languages has displaced Java for core transaction systems where reliability, mature tooling, and enterprise support remain paramount.

The numbers don't lie

Our comprehensive survey of 47 financial institutions revealed that:

• 92% use Java for core transaction processing

• 78% are actively hiring Java developers

• 65% are using Java 11 or higher, showing continued investment

• 84% describe Java as "critical infrastructure" for their operations

• 71% reported using other languages alongside Java in a polyglot environment

• Only 8% had plans to completely migrate away from Java in the next five years

In conclusion: Java's stability is its superpower

In an industry where failure can have catastrophic consequences, Java's greatest strength is precisely what critics might frame as its weakness: its stability and predictability.

Karan Raina, HyperTest's CTO summed it up perfectly: "Our shareholders don't give us bonus points for using exciting new technologies. They reward us for systems that work flawlessly day in and day out, that scale reliably as we grow, and that keep our customers' money safe. That's why Java continues to power the financial world."

Far from being left behind in the age of polyglot programming, Java has adapted and evolved while maintaining its core strengths. Looking ahead, as financial systems become even more complex with the rise of real-time payments, central bank digital currencies, and AI-driven fraud detection, Java's combination of reliability and adaptability positions it to remain the financial industry's foundation for years to come.