Open-source AB Tasty alternatives

PostHog is an open-source platform that bundles the tools product teams use to understand and improve what they ship. It captures event data, user sessions and errors in one place, and its newer self-driving mode aims to turn signals such as errors, rage clicks and failed queries into researched reports and pull requests that engineers review and merge.

The product suite includes product analytics with autocapture or manual instrumentation and SQL analysis, web analytics with a dashboard resembling Google Analytics, session replays for web and mobile, feature flags, experiments with statistical measurement, surveys, error tracking, logs, a data warehouse and a customer data platform. The back end is Python and the front end is React and TypeScript.

PostHog's repository license is listed as 'Other' on GitHub, so check which parts are open source and which are enterprise-only. It can be self-hosted, and the company also runs a managed cloud service. It suits product and engineering teams that prefer a single tool over separate analytics, flagging and replay vendors.

GrowthBook combines feature flagging, experimentation and product analytics in one open-source platform. The project's stated philosophy is that most companies cannot build an in-house platform of this kind, so it aims to give them the flexibility of one without the effort, instead of paying for closed SaaS tools or stitching together unmaintained libraries.

Feature flags support targeting, gradual rollouts and experiments, with 24 SDKs including React, Python, Android and iOS. The statistics engine offers methods such as CUPED, sequential and Bayesian testing, post-stratification, bandits and sample ratio mismatch checks. It is warehouse native, querying data sources such as BigQuery, Snowflake and Databricks, with metrics defined in flexible SQL. A built-in analytics suite supports dashboards, and there are webhooks, a REST API and an MCP server.

You can start with a free GrowthBook Cloud account or run it yourself with Docker and the prebuilt public image. The repository lists the licence as Other, so review the licence terms for the exact conditions on the open-source and enterprise parts. It suits product and data teams that want to run experiments on their own warehouse data.

Flagsmith is a feature management platform, released as open source, offering feature flags, remote configuration and experimentation. It provides three deployment options: self-hosted, available as a free open-source build or as a fully supported Enterprise edition, a private cloud and a standard cloud service. Its partnership with OpenFeature is intended to avoid vendor lock-in.

Teams wrap sections of code in flags and toggle features on or off remotely for different environments, users or segments without deploying new code. Segments let you release to beta testers and gather feedback, and A/B and multivariate tests run on top of segments. Organisation management covers orgs, projects and roles for team members, and SDKs cover more than 15 languages with support for frameworks such as React and Next.js, plus integrations and an MCP server.

Flagsmith is written in Python and React, ships as Docker images and is released under the BSD 3-Clause licence for the open-source build. It suits product and engineering teams that want controlled rollouts and remote configuration across web, mobile and server-side applications.

FeatBit is an open-source feature flag management platform that developers can host themselves. It helps teams ship code safely by testing in production, releasing to a small share of users first, expanding gradually, and recovering instantly from errors without redeploying. It is written in C# and .NET and released under the MIT license.

Teams control who sees each feature and when, release to specific target users, and run A/B tests and experiments to measure outcomes. Topics list remote configuration, entitlement, release as code, and progressive delivery. SDKs are available for languages including .NET, Python, and TypeScript, and the project provides documentation, a Discord community, and an online demo.

FeatBit suits engineering teams adopting continuous delivery who want an enterprise-style flag system under their own control, as an alternative to commercial platforms such as LaunchDarkly.