Flagsmith

Flagsmith provides a dashboard, API and SDKs for defining and controlling feature flags, remote configuration and A/B testing across web, mobile and server‑side applications. Users can toggle features, apply granular segmenting rules, and roll out changes without redeploying code, while the platform supports staged rollouts, percentage targeting and user‑trait based segmentation.

The service is available as a self‑hostable, open‑source package under the BSD‑3‑Clause license, with a free tier and no subscription requirement for core functionality. It includes SDKs for more than fifteen languages and frameworks, enabling integration with existing stacks and allowing real‑time flag evaluation via a RESTful API.

Designed for developers, engineering teams and software architects, Flagsmith offers role‑based access control, organization and project management, and optional enterprise‑level governance features. Deployment options include SaaS, private cloud and on‑premise installations, giving teams flexibility to host the platform in the environment that meets their security and compliance needs.