Best / Feature flags
Best open-source Feature flags
The best self-hosted feature-flag split in the c17.io catalog is Unleash for an AGPL-3.0 control plane (the published LaunchDarkly/Split.io stack), Flagsmith for BSD-3-Clause flags and remote config, GrowthBook when you want MIT-core flags and experiments (skip enterprise/; GitHub license field is unset), and PostHog when flags sit next to product analytics you already host. This is not LaunchDarkly's every experiment SKU. You still wire SDKs in the apps.
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Ranked picks
1
UnleashAGPL-3.0 feature management — the c17 LaunchDarkly/Split.io path.
When to pick it: A flag service the SDKs already know.
13,891 stars in the catalog
2
FlagsmithBSD-3-Clause flags, remote config, and experiments — /compare/unleash-vs-flagsmith.
When to pick it: Remote config if Unleash is not the shape.
6,610 stars in the catalog
3
GrowthBookMIT core flags and experiments; skip enterprise/. GitHub license field is Other — /compare/growthbook-vs-unleash.
When to pick it: Experimentation next to flags.
8,521 stars in the catalog
4
PosthogProduct analytics that can also hold flags — already on /best/analytics.
When to pick it: Flags next to funnels you already self-host.
How they compare
| Tool | License | Self-host | Best for |
|---|---|---|---|
| Unleash | GNU Affero General Public License v3.0 | Easy | A flag service the SDKs already know. |
| Flagsmith | BSD 3-Clause "New" or "Revised" License | Easy | Remote config if Unleash is not the shape. |
| GrowthBook | Other | Medium | Experimentation next to flags. |
| Posthog | Not listed | Medium | Flags next to funnels you already self-host. |
Related pages
- Unleash / Flagsmith stack
- PostHog stack
- Replace LaunchDarkly
- Replace Split.io
- Replace ConfigCat
- Replace Statsig
- Replace Hotjar
- Replace Amplitude
- Replace Heap
- Replace FullStory
- Replace LogRocket
- Replace PostHog Cloud
- Replace Pendo
- Replace Smartlook
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- Unleash vs Flagsmith
- GrowthBook vs Unleash
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FAQ
- Unleash or Flagsmith?
- Unleash if you want the published LaunchDarkly path. Flagsmith if you want BSD remote config — /compare/unleash-vs-flagsmith.
- What about GrowthBook?
- Useful. Skip enterprise/. GitHub's license field is unset — /compare/growthbook-vs-unleash.
- Is this PostHog?
- PostHog is product analytics first. Use it for flags if you already run that box.
- Are these free?
- Unleash is AGPL-3.0. Flagsmith is BSD-3-Clause. GrowthBook core is MIT if you skip enterprise/. You pay hosting. Template users never pay c17.
- How do I deploy it?
- Open /stacks/unleash-flags. Persist Postgres. Create one flag and wire one SDK.
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