As Facebook’s user base and family of applications grows, it’s important to ensure correctness and performance across many hardware and software platforms. Managing all these combinations for testing would be an operational impossibility for small teams focused on a particular service or feature. To make testing scalable and reliable, Evan Snyder, Production Engineer at Facebook, discusses how Facebook built a resource management system called One World to allow teams to dependably request the platforms required via a unified API, no matter its type or location.