Feature Flags at Scale: Designing a Distributed Control System for Production Behavior (opens in new tab)

The Counterintuitive Truth: Feature Flags Are Not Config Files Most engineers first encounter feature flags as a simple abstraction: a key-value lookup that returns true or false. That mental model works fine for a single service handling a few hundred requests per minute. It becomes actively dangerous at scale. A mature feature flag system isn't a config file with an API wrapper — it's a distributed control plane. The distinction matters architecturally. A control plane manages the real-time...