Node.js Feature Flags in Production: LaunchDarkly, Unleash, and Custom Toggles

Node.js Feature Flags in Production: LaunchDarkly, Unleash, and Custom Toggles The safest way to deploy new code is to ship it to production without turning it on. Feature flags — also called feature toggles — make this possible. They decouple code deployment from feature activation, letting you release to a subset of users, run A/B tests, and kill features instantly without a redeploy. This guide covers three approaches for production Node.js: the LaunchDarkly SDK (managed, enterprise-grade), Unleash (self-hosted, open-source), and a zero-dependency custom toggle system you can ship in an afternoon. All production-ready patterns. Why Feature Flags Change How You Deploy Without feature flags, the typical production incident goes like this: you deploy, something breaks, you redeploy the previous version. That rollback takes 5–15 minutes, during which users see the broken behavior. With feature flags: you disable the flag. The rollback is instantaneous. No redeploy, no pipeline wait, no