Wrap code in a flag, then toggle it per environment, per user, per segment, or by percentage - no redeploy required: Flagsmith is an open-source feature flag and remote config platform. Every flag doubles as remote config, carrying string, number, or JSON values, so functional and visual changes ship to production without a code push. Segments are the targeting engine: build them from stored user traits, then release to beta testers first, test in production by exposing features only to internal teams, or run canary deployments to a small percentage before going wide - segment membership changes instantly without app updates. Multivariate flags split traffic across two or more variations for A/B/n testing, with flag events flowing into Amplitude, Mixpanel, or Segment for analysis. SDKs cover 15+ languages including TypeScript, .NET, Java, Python, and Go, with framework support for React, Next.js, and mobile, plus local evaluation for latency-sensitive paths. Organizations, projects, and roles keep multi-team setups tidy. Core functionality - unlimited flags, remote config, targeting, multivariate flags - is BSD-3-Clause licensed with an explicit commitment that it stays open. Self-hosting suits privacy-conscious teams: flag rules and user traits stay on your infrastructure, deployable via Docker or Kubernetes with Helm.