The best Feature flags & experimentation
Every option ranked — open-source, self-hostable, and commercial — by our transparent Sovereignty Score, with honest trade-offs so you choose what fits you, not us.
Ship code dark, turn it on for 1% of users, roll it back without a deploy. Priced per connection and per user, which is how a simple boolean becomes a five-figure line item.
L3Infrastructure — layer 3 of the AI stack- 1
Unleash
Top pickOpen sourceThe most complete open feature-flag platform, and it self-hosts properly.
Open-source server free and self-hostable. Hosted and enterprise tiers are paid. · in our LaunchDarkly comparison →
What is Unleash? →89sovereignty - 2
OpenFeature
Open sourceNot a platform — the standard that makes the platform swappable.
Free and open source. It is a specification and a set of SDKs. · in our LaunchDarkly comparison →
What is OpenFeature? →97sovereignty - 3
Flipt
Open sourceFlags defined in Git, evaluated by one Go binary.
Free and open source. One binary on hardware you already have. · in our LaunchDarkly comparison →
What is Flipt? →93sovereignty - 4
Flagsmith
Open sourceBSD-licensed flags with remote config, and no copyleft to reason about.
Open source free and self-hostable. Hosted plans have a free tier and paid tiers above it. · in our LaunchDarkly comparison →
What is Flagsmith? →90sovereignty - 5
GrowthBook
Open sourceFlags plus a real statistics engine — the experimentation answer.
Self-hostable core free. Cloud and enterprise tiers are paid. · in our LaunchDarkly comparison →
What is GrowthBook? →83sovereignty
Is it free?
The free tier, its real limits and where you start paying — read from each vendor's own pricing page and dated.
Run these yourself
What each one actually needs — real RAM, honest running cost, and the setup time nobody quotes.
Replacing a specific tool?
Head-to-head comparisons for each popular feature flags & experimentation product.
Straight head-to-heads
Two feature flags & experimentation tools, side by side — verified facts and a plain verdict.