flagd

flagd is a feature flag evaluation engine. Think of it as a ready-made, open source, OpenFeature-compliant feature flag backend system.

With flagd, you can:

• modify flags in real-time
• define flags of various types (boolean, string, number, JSON)
• use context-sensitive rules to target specific users or user traits
• perform pseudorandom assignments for experimentation
• perform progressive roll-outs of new features
• aggregate flag definitions from multiple sources
• expose aggregated flags as a gRPC stream to be used by in-process providers
• expose OFREP service for configured flags

It doesn't include a UI, management console or a persistence layer. It's configurable entirely via a POSIX-style CLI. Thanks to its minimalism, it's extremely flexible; you can leverage flagd as a sidecar alongside your application, an engine running in your application process, or as a central service evaluating thousands of flags per second.