The ultimate guide to building an internal feature flagging system

Feature flagging is a complex area within development tools, often misunderstood due to misconceptions about its functionality and sophistication. While it may seem that a simple database could suffice, a robust feature flagging platform offers essential capabilities such as client-side availability with security, rapid evaluation, high uptime, and versatile user targeting. The guide discusses the intricate design decisions required to build a feature flagging platform, addressing both client-side and server-side implementations and examining their advantages and challenges. It emphasizes the importance of providing ergonomic SDKs, logging infrastructure, and a user-friendly UI, along with additional features like non-boolean returns and streaming. The guide draws on the experience of building and scaling Statsig, suggesting that developing a high-quality feature flagging system is an extensive endeavor, requiring significant time and resources, but offering the potential for substantial control and flexibility in feature deployment and testing.