Feature Flags
3 open source tools compared. Sorted by stars. Scroll down for our analysis.
| Tool | Stars | Velocity | Score |
|---|---|---|---|
 Unleash Open-source feature management platform | 13.5k | +20/wk | 83 |
 GrowthBook Open source feature flags and experimentation | 7.7k | +19/wk | 75 |
 Flagsmith Open source feature flagging and remote config | 6.3k | +11/wk | 79 |
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Our Analysis
Unleash is a feature flag platform that handles gradual rollouts, user targeting, and instant kill switches without redeploying. Think of feature flags as on/off switches for your code that you can flip without shipping new code. TypeScript, Apache 2.0. Supports gradual rollouts, A/B testing, user segmentation, and environment-specific flags (enable in staging but not production). SDKs for every major language. Self-hosted Open Source is free with no user or flag limits. Docker Compose gets you running in minutes. The free version includes everything a small team needs: flags, strategies, environments, API access, and the admin UI. Pro plan: $80/mo for 5 team members, adds change requests (approval workflows), banners, custom event tracking. Enterprise is custom with SAML SSO, SCIM, audit logs, and service accounts. Solo: self-host free, it's trivial to run. Small teams (2-10): self-host free unless you need approval workflows. Medium teams: Pro at $80/mo or self-host with custom RBAC. Large teams: Enterprise for SSO and compliance, or evaluate LaunchDarkly if you want managed. The catch: the open source version doesn't have change requests (peer review before toggling flags in production). For regulated environments where you need an audit trail of who changed what and who approved it, that's a paid feature. And the market leader LaunchDarkly has a richer integration ecosystem.
Grist combines spreadsheets and databases: it looks like a spreadsheet but stores structured data with types, relations, and access controls underneath. Feature flags let you ship code that's off by default and turn it on for specific users. The experimentation side tracks whether those changes actually move your metrics. The free self-hosted version is complete: unlimited flags, unlimited experiments, unlimited seats. That's rare. Most feature flag tools gate seats or experiment volume. The cloud version has a free tier too: 3 seats, 1,000 experiment subjects. Self-hosting runs as a Docker container with MongoDB and an optional data warehouse connection (BigQuery, Snowflake, Postgres). Setup takes 30-60 minutes if you know Docker. The real work is connecting your analytics data source. Paid cloud starts at $20/seat/mo (Pro) for teams wanting managed hosting, advanced permissions, and visual editor. Enterprise adds SSO, audit logs, and SLAs. The catch: the experimentation engine is powerful but requires a data warehouse. If you just want flags, this is overkill. For flags-only, LaunchDarkly's free tier or Unleash might be simpler. But if you want flags AND experiments in one tool without paying per-seat, self-hosted GrowthBook is hard to beat.