How to Build Your Own Feature Flags in About 100 Lines of Code

A software developer has outlined a lightweight, self-built alternative to commercial feature flag platforms like LaunchDarkly, Flagsmith, and Split, aimed at small teams and early-stage SaaS companies. Feature flags are runtime switches that control whether code executes without requiring a redeployment, enabling workflows such as gradual rollouts, kill switches for risky changes, and per-user targeting. The author argues that for teams managing only a handful of flags, purchasing a vendor solution is often premature, since commercial platforms charge based on seats and monthly active users — costs that grow as the product scales. A self-owned implementation of roughly 100 lines of code can replicate the core capabilities while eliminating recurring licensing fees. The piece positions the build-vs-buy decision as a matter of matching infrastructure complexity to actual team needs.