The Unkillable Code: Why 8 “Ancient” Programming Languages Are Thriving in 2025
In the fast-moving world of technology, where new frameworks and languages emerge with dizzying speed, a quiet counter-revolution is underway. Against the backdrop of AI hype and Silicon Valley’s obsession with the “next big thing,” a cohort of programming languages born in the 20th century isn’t just surviving—it’s thriving. These are not digital fossils kept alive by nostalgia; they are robust, mission-critical tools that continue to power global finance, scientific discovery, defense systems, and everyday business operations. This is the story of eight old programming languages that developers and the global economy simply cannot quit.
The Persistent Eight: A Snapshot of Vitality
The following table outlines the enduring roles and modern evidence of these languages’ vitality, demonstrating they are far from obsolete.
| Language (Year Born) | Enduring Role & Domain | Evidence of Vitality in 2025 |
| COBOL (1959) | Core banking, insurance, and government transaction systems. | Powers an estimated $3 trillion in daily financial transactions. Actively updated with object-oriented features (COBOL-2023). |
| Fortran (1957) | High-performance scientific computing: climate modeling, physics, fluid dynamics. | Ranked #12 on the TIOBE Index (Dec 2025), above Rust and PHP. Its compilers are decades-optimized for raw number crunching. |
| Ada (1980s) | Safety-critical systems in aerospace, aviation, rail, and defense. | Ranked #14 on the TIOBE Index. The Ada 2022 standard focuses on safe parallelism for modern hardware. |
| C (1972) | Operating systems, embedded electronics, and performance-critical software foundations. | Consistently top 3 in all language rankings. The #2 language on the TIOBE Index as of December 2025. |
| Pascal/Delphi (1970) | Rapid development of reliable desktop and cross-platform applications. | Delphi/Object Pascal holds position #11 on the TIOBE Index. Renowned for fast compilation and maintainable code. |
| Perl (1987) | Text processing, system administration, legacy system maintenance, and bioinformatics. | Made a surprising surge to #9 on the TIOBE Index in late 2025. The CPAN repository remains a massive asset. |
| Visual Basic (1991) | Internal business tools, office automation, and rapid prototyping within the Microsoft ecosystem. | Holds a strong position at #7 on the TIOBE Index, proving its widespread use in enterprise environments. |
| Python (1991) | AI/ML, data science, scripting, and web backends. The “youngest” on this list, but already grappling with legacy. | The undisputed #1 language across all major indexes. Its “old versions” are actively maintained via virtual environments. |
Why the Old Guard Refuses to Retire: The Logic of Legacy
The persistence of these languages is not an accident or a failure of innovation. It is a rational, economic, and engineering-driven choice grounded in several powerful arguments.
- The Immense Risk and Cost of the “Big Rewrite.”The most compelling reason is the monumental risk associated with replacing a working system. The business logic in a decades-old COBOL system for a major bank represents countless human-years of debugging, optimization, and real-world stress-testing. Rewriting it in a modern language like Java or Go introduces new bugs, new security vulnerabilities, and astronomical costs with zero functional benefit to the end-user. As one article bluntly puts it, “The logic in software doesn’t wear out or rot over time. So why toss away perfectly debugged code?”
- The Triumph of Pragmatism Over Hype.The tech industry is driven by trends, but global enterprises run on stability and return on investment. For a CFO, the question isn’t whether a system uses a fashionable language, but whether it processes payments accurately, 24/7. These older languages are “battle-tested”—they have proven they can handle the load. The trade-off is clear: cutting-edge syntax versus proven, dividend-paying reliability.
- Domain-Specific Superiority and Modernization.In their niches, these languages are often still the best tool for the job. Fortran remains unbeaten for large-scale numerical computation because its compilers have been optimized for over half a century. Ada was mathematically designed for safety and is indispensable where a software failure means loss of life. Furthermore, these languages are not frozen in time. They have evolved, with modern versions adding object-oriented capabilities, better parallelism, and improved tooling. GNU Cobol and modern IDEs have also lowered the barrier for new developers to work with these systems.
- The Economics of Talent and System Longevity.There is a persistent and lucrative demand for developers who can maintain these legacy systems. While the pool of COBOL programmers may be aging, this scarcity makes their skills highly valuable. Companies face a clear choice: pay a premium to maintain a stable, critical system, or bet the business on a risky, multi-million dollar migration.
A Future Shaped by the Past and AI
Looking ahead, the role of these languages is being shaped by two major forces. First is the pragmatic understanding that software longevity is a feature, not a bug. The industry is recognizing that constantly chasing new frameworks can lead to fragile, over-engineered systems that are hard to maintain. The “old” languages represent a philosophy of building durable infrastructure.
Second, the rise of AI-assisted programming (like GitHub Copilot) presents a fascinating twist. Large Language Models are trained on publicly available code, which is dominated by popular languages. This creates a feedback loop that could further cement the position of widely used languages while making it harder for new ones to emerge. Ironically, AI might make it easier to generate and maintain code in some of these older languages, potentially extending their lifespans even further.
In the end, the story of these eight languages is a lesson in technological maturity. It reminds us that in the real world—far from the hype cycles of developers’ conferences—the best language for the job is often the one that already works, perfectly and profitably. They are the unkillable code, and they will likely underpin the critical systems of our world for decades to come.
