Answer: Defense Department Contracts

While it’s difficult to say with absolute certainty what the oldest computer program in use is (as there might be an incredibly old program somewhere in the bowels of an old company or bank office still cranking away in anonymity), we can say with certainty that the oldest verified computer program still humming along is tasked with managing U.S. Department of Defense contracts.

First brought online back in 1958, Mechanization of Contract Administration Services (MOCAS) has, for decades, served as the hub of the entire Department of Defense’s contract tracking. Written in COBOL, the system has received numerous upgrades over the years in terms of its interface—it was originally controlled using punch cards, then CRT terminals, and now it’s buried beneath layers of web interfaces and GUIs—but beneath the various interfaces, it’s still largely the same exact program brought on line to handle Cold War-Era contracts.

Why is the software so long lived? Surely there’s a more modern system that the Department could use, right? The biggest impediment to any upgrade is simply the amount of data the software handles and the wrench it would throw into the daily operations of the Department if they replaced it. The MOCAS software handles roughly 340,000 contracts at any given time, totaling over a trillion dollars in obligations. Transitioning old contracts or even simply starting all new contracts in a newer system creates a mess that the Department simply isn’t willing to deal with unless there is an excellent and smooth path laid out between the old software and its successor.