Flagsmith

Flagsmith is an open-source feature flag and remote configuration platform that lets development teams turn features on or off, roll them out gradually, and control app behavior without deploying new code. Developers wrap features in flags, then manage them across environments (development, staging, production) from a dashboard or API — enabling safer releases, targeted rollouts, kill switches, and experimentation. Because it is open source, teams can self-host for full control over their data, or use Flagsmith’s managed cloud.

The platform covers modern release management. Feature flags and remote config change behavior instantly per environment and per user segment; percentage rollouts and A/B testing enable gradual releases and experiments; and identity/segment targeting delivers different experiences to different users. Flagsmith provides SDKs for web, mobile, and server languages, an API, integrations (analytics, Slack, Jira), and governance features (roles, change requests, audit logs) on higher tiers. Its open-source core plus self-hosting option is a key draw for teams with data-residency or control requirements.

Flagsmith serves engineering and product teams managing feature releases and experiments. It offers a free-forever plan ($0, 50,000 API requests/month, 1 team member, unlimited flags), a Start-Up plan around $45/month ($40 annually; 1M requests, 3 members, A/B testing), a Scale-Up plan around $300/month ($250 annually; 5M+ requests, SSO, governance), and custom Enterprise; the open-source version is free to self-host. It competes with LaunchDarkly, Unleash, ConfigCat, and Split, differentiating on open-source with a self-hostable option and straightforward pricing.