Thank you! A very good introduction to Feature Flags. We use them a lot. Front-end feature flags are managed via object freezing and/or closure functions. Backend feature flags are managed using Memcached key/value configuration loaded from the configuration database. I know you warned against home-grown solutions; we did look at managed services a bit a while back but wasn’t a good fit then. Our memcache based key/value configuration works like the old Windows registry system and allows us to control feature flags and many other configuration points.