Feature Flags in Node.js: Express and Fastify Guide

This was originally published on rollgate.io/blog/feature-flags-nodejs . Why Feature Flags in Node.js? Node.js powers a huge slice of production backends — REST APIs, GraphQL gateways, background workers, BFF layers, real-time services. All of them share the same release problem: you want to ship code continuously, but you do not want every deploy to be a product change. Feature flags in Node.js decouple deployment from release. You push code to production behind a flag and decide later who sees