COBOL in the Wild: What Developers Are Building on Mainframes Today

The idea of a COBOL developer often conjures images of a relic from a bygone era of computing. However, a deep dive into the experiences of those working with the language today reveals a different story. COBOL is not just surviving; it's actively powering the core of major industries, and the developers maintaining these systems possess a unique and valuable skill set.

Where COBOL Still Reigns Supreme

COBOL's enduring presence is most prominent in sectors that were early adopters of computing and demand extreme reliability for high-volume transaction processing.

Banking and Finance: This is the most cited domain. COBOL is used for core banking systems, processing end-of-day batch jobs, managing ACH transfers, and handling countless financial transactions. The backend is often a combination of DB2, IMS, and VSAM files.
Insurance: Insurance companies rely on COBOL for managing policies, processing claims, and handling billing. The complexity of legacy insurance products, some with rules grandfathered in from decades ago, makes migrating these systems incredibly difficult.
Government: From state-level health insurance claim processing to federal payroll systems (like Canada's Phoenix system) and pension payments, COBOL is deeply embedded in public sector infrastructure. New legislation often requires developers to translate policy changes directly into COBOL code.

The Life of a Mainframe Developer

The work is a mix of maintaining decades-old code and developing new programs. "New" development is often in response to regulatory changes or new business products, frequently extending existing applications rather than starting from scratch.

The Tech Stack: While COBOL is the language, the environment is just as important. Developers work on powerful IBM Z mainframes running z/OS. Key components of the stack include:

Transaction Managers: CICS and IMS are frequently mentioned for managing real-time transactions.
Databases: DB2 is a common relational database, but hierarchical databases like IMS DB and file access methods like VSAM are still prevalent.
Development Tools: While many still work on traditional green-screen terminals (often emulated, like 3270), modern tools are making inroads. Some teams use Git for version control and IDEs like IBM's IDz or even VS Code with the Zowe extension to interact with the mainframe.

The Culture and Compensation: A significant cultural difference exists between mainframe developers and the "move fast and break things" ethos of the startup world. Mainframe culture prioritizes stability, reliability, and deep business domain knowledge. Developers often have a long tenure and become experts in the specific business processes their code manages.

Contrary to the popular myth of exorbitant salaries, compensation for full-time COBOL developers is often on par with or even lower than other software engineering roles. The high fees are typically commanded by highly specialized, independent consultants brought in to solve critical problems on unique, quirky systems.

The Immense Challenge of Modernization

If these systems are old, why not just replace them? The answer is complex and risky.

Undocumented Logic: Decades of business rules and logic are embedded directly in the code, often with little to no external documentation. This "tribal knowledge" is a massive barrier to rewriting systems accurately.
Failed Migrations: Many companies have spent millions on failed attempts to migrate to newer platforms like SAP or custom Java systems. The risk of disrupting a system that reliably processes billions of dollars is too high.
Alternative Paths: Instead of a full rewrite, many organizations pursue incremental modernization. This can involve running COBOL on commodity hardware using compilers like Micro Focus COBOL, wrapping mainframe transactions with modern REST APIs, or integrating with platforms like Kafka.

For those interested in exploring this world, several resources are available. IBM Z Xplore provides free, hands-on access to a live z/OS system. Coursera offers an "Intro to Mainframe" professional certificate, and the Hercules emulator allows you to run mainframe operating systems on a PC.