One of the intriguing parts of the WhatsApp story is that it has achieved such enormous scale with such a tiny team. When the company was acquired by Facebook, it had 35 engineers and reached more than 450 million users. Today, it employs only about 50 engineers, though the number of WhatsApp users has doubled, and this tiny engineering staff continues to run things almost entirely on its own. In a world where so many internet services are rapidly expanding to millions upon millions of users, WhatsApp shows the way forward—at least in part. WhatsApp doesn’t talk much about its engineering work—or any other part of its operation, for that matter—but yesterday, at an event in San Jose, California, WhatsApp software engineer Jamshid Mahdavi took the stage to briefly discuss the company’s rather unusual methods. Part of the trick is that the company builds its service using a programming language called Erlang. Though not all that popular across the wider coding community, Erlang is particularly well suited to juggling communications from a huge number of users, and it lets engineers deploy new code on the fly. But Mahdavi says that the trick is as much about attitude as technology. Mahdavi joined WhatsApp about two years ago, after the startup was up and running, and its approach to engineering was unlike any he had seen—in part because it used Erlang and a computer operating system called FreeBSD, but also because it strove to keep its operation so simple. “It was a completely different way of building a high-scale infrastructure,” he said on Monday. “It was an eye-opener to see the minimalistic approach to solving … just the problems that needed to be solved.”