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GrowthBook

Open-source feature flags and A/B testing platform

freemiumopen sourceupdated Aug 16, 2026

GrowthBook is an open-source platform for feature flags, A/B testing, and product experimentation. It includes Bayesian and frequentist statistics engines, warehouse-native analytics connecting to BigQuery, Snowflake, and Databricks, and SDKs for 15+ languages. GrowthBook supports targeting rules, gradual rollouts, and an MCP server for AI agent integration. Self-hostable via Docker.

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A detailed review by the aicoolies team — click to read

GrowthBook provides the most feature-complete open-source alternative to LaunchDarkly for teams that need both feature flags and experimentation capabilities. Its feature flag system supports boolean, multivariate, and JSON flags with targeting rules based on user attributes, percentage-based rollouts, and prerequisite flags. The experimentation engine runs statistical analysis using Bayesian, frequentist, sequential, and CUPED methods, giving product teams rigorous A/B testing without third-party analytics dependencies.

What sets GrowthBook apart from simpler feature flag tools is its warehouse-native analytics architecture. Instead of collecting its own event data, it connects directly to your existing data warehouse — BigQuery, Snowflake, Databricks, Redshift, ClickHouse, Mixpanel, or Postgres — to compute experiment results. This means teams use their existing event tracking and data pipelines rather than implementing a parallel analytics stack. The visual experiment editor lets non-technical users create and manage experiments through a web interface.

With 7.9K+ GitHub stars and active development under mixed licensing, GrowthBook has become a default choice for engineering teams that want self-hosted experimentation infrastructure. Most non-enterprise code is available under MIT Expat terms, while enterprise directories use the GrowthBook Enterprise License. SDKs cover JavaScript, React, Python, Ruby, Go, Java, PHP, Swift, Kotlin, Flutter, and more, and the platform includes REST APIs, webhooks, and an MCP Server for feature-flag workflows.

Pricing

Starter free; Pro $40/seat/month; Enterprise custom

full pricing breakdown →

Platforms

Docker, self-hosted — SDKs for 15+ languages

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Comparisons

GrowthBook vs Flagsmith — Feature Flags with Experimentation vs Simple Feature Toggles

GrowthBook and Flagsmith are the two leading open-source feature flag platforms, but they target different needs. GrowthBook combines feature flags with a full experimentation and A/B testing engine, while Flagsmith focuses on straightforward feature management with simpler deployment. This comparison helps teams choose based on whether they need experimentation capabilities or just feature toggles.

GrowthBookFlagsmith

FAQ

What is GrowthBook?

GrowthBook is an open-source platform for feature flags, A/B testing, and product experimentation. It includes Bayesian and frequentist statistics engines, warehouse-native analytics connecting to BigQuery, Snowflake, and Databricks, and SDKs for 15+ languages. GrowthBook supports targeting rules, gradual rollouts, and an MCP server for AI agent integration. Self-hostable via Docker.

Is GrowthBook free?

GrowthBook offers a free tier alongside paid plans. Starter free; Pro $40/seat/month; Enterprise custom

Is GrowthBook open source?

Yes — GrowthBook is open source.

What are the best GrowthBook alternatives?

The top editor-verified GrowthBook alternatives are Flagsmith, Resolve AI.

How does GrowthBook score in our review?

Our hands-on review scores GrowthBook 87/100 overall, based on speed, privacy, and developer-experience testing.