Flagsmith

A feature flag and remote configuration service that lets you change how an application behaves without shipping a new release. Flags are defined in a web interface, targeted by percentage rollout, user, segment or rule, and delivered to browsers, mobile apps and backend services through official SDKs, which also carry remote config values adjustable on the fly.

Engineering teams use it to release features gradually, run A/B tests, limit access to beta users, and switch behaviour off during an incident.

Self-hosting keeps flag definitions on your systems, avoids per-user or per-environment billing, and makes migration to another flag system largely a matter of swapping the SDK.