Experimentation & feature flags · Flagsmith

Flagsmith

Open-source (BSD-3-Clause) feature-flag and remote-config platform with basic A/B testing on flagged traffic, self-hostable or cloud.

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Flagsmith manages feature flags, remote configuration, and user/segment targeting through SDKs across web, mobile, and server platforms, with A/B testing available on top of flag rollouts rather than as a warehouse-native statistical engine. Its core functionality — flags, remote config, targeting rules, and multivariate flags — is open source under the BSD-3-Clause license (a small number of components are MIT-licensed), and it can be fully self-hosted or run on Flagsmith's managed cloud with the same feature set. It targets engineering teams that want an open, inspectable flagging system with straightforward experimentation, rather than the deeper statistical tooling (Bayesian, sequential, CUPED) found in warehouse-native platforms like Eppo, Statsig, or GrowthBook.

At a glance

Vendor Flagsmith
Pricing model Free tier + paid plans
Free tier Yes
Deployment Cloud, Self-hosted
Open source Yes (BSD-3-Clause)
Best for Engineering teams wanting a fully open-source, self-hostable flagging system with light A/B testing.

Pricing

Free tier up to 50,000 requests/month; Start-Up from $40/month; Scale-Up from $250/month; Enterprise custom.

Plan Price Notes
Free $0/month up to 50,000 requests/month, 1 team member
Start-Up from $40/month (annual) up to 1,000,000 requests/month, 3 team members
Scale-Up from $250/month (annual) 5,000,000+ requests/month, SAML/SSO, 5 members included
Enterprise custom ("Contact Sales") tailored hosting (cloud/private cloud/self-hosted), SLA

Prices read from the vendor's own page on September 21, 2026. Vendors change prices; check the source before you budget.

Features

  • Feature flags and remote configuration
  • User and segment targeting rules, multivariate flags
  • A/B testing on flagged rollouts
  • Open-source core (BSD-3-Clause), self-hostable
  • 2FA and SAML/SSO on higher tiers
  • REST API and SDKs across major platforms

Integrations

Profile last reviewed September 21, 2026

Alternatives

Unleash Open-source feature-flag platform with rollout-based experimentation, moved from Apache-2.0 to AGPLv3 licensing in mid-2026. LaunchDarkly Feature-flag management platform that also runs experiments on flagged rollouts, reading event data it collects itself rather than the warehouse. Harness Feature Management & Experimentation (formerly Split) Feature-flag platform with built-in statistical experimentation, acquired by Harness and sold as an Enterprise-plan module (Harness FME).

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Terms to know

A/B testing A controlled experiment that compares two variants to measure which one produces a better outcome. CUPED (controlled-experiment using pre-experiment data) A variance-reduction technique that uses each user's pre-experiment behavior to sharpen an experiment's estimate without adding more traffic.

Related guides

How to choose an experimentation and feature-flag platform Pick by where your experiment data comes from — flag telemetry or your own warehouse — and which statistical engine your team trusts, not feature count.