Why WhatsApp Only Needs 50 Engineers for Its 900M Users (2015)
&gt;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. &quot;It was a completely different way of building a high-scale infrastructure,&quot; he said on Monday. &quot;It was an eye-opener to see the minimalistic approach to solving ... just the problems that needed to be solved.&quot;