Unleash

Unleash is an open source feature management platform positioned as an alternative to LaunchDarkly and Split. It lets teams ship code to production behind a feature flag and control who sees a feature through activation strategies, rather than coordinating a release around a full deploy. Unleash describes itself as the most popular open source feature flagging solution on GitHub, and it supports 15 official client and server SDKs plus more than 15 community SDKs, with compatibility across any language or framework.

Key features

• Activation strategies: enable or disable features for specific users or segments without redeploying the application.
• Canary releases and gradual rollouts: ship a change to a subset of traffic before a full release, reducing the risk of a bad change reaching every user at once.
• Kill switches: turn a flag off instantly if a feature causes problems in production, without a code deploy.
• Broad SDK coverage: 15 official SDKs and 15+ community SDKs across languages and frameworks, with support and documentation for building a custom SDK.
• Environment and project overview: see every feature flag across all environments, applications, and services in one place, instead of tracking flags per service.
• Parallel feature branches avoided: since flags gate code paths instead of branches, teams can work on multiple features in the same codebase simultaneously without long-lived feature branches.
• Enterprise tier: adds role-based access control, change requests, single sign-on, and SCIM user provisioning on a hosted plan, along with unlimited projects and environments.

Self-hosting and deployment

A local instance starts with git clone [email protected]:Unleash/unleash.git, cd unleash, then docker compose up -d, after which the admin UI is available at localhost:4242 (default login admin / unleash4all). Guides are provided for deploying to production on Heroku and DigitalOcean, and the project can also be run directly from source with Node.js, following the step-by-step setup in the contributing guide.

Getting started

After the local instance is running, connecting an SDK requires a frontend API URL and client key, or a backend API URL and API token; both are printed in the docker-compose configuration for local development. Checking a flag in application code is a single function call, for example unleash.isEnabled("AwesomeFeature") in Java, with the same pattern repeated across each of the official SDKs. Teams that want to try Unleash before setting anything up can open the live demo in a browser with no signup required, which includes the core feature set on a shared instance, or start a 14-day free trial of the hosted Enterprise product for a dedicated instance.

Community support runs through a public Slack workspace for open questions about Unleash or feature toggling in general, and GitHub Issues for bugs and improvement ideas. Contributors need to read and agree to the Unleash Contributor License Agreement before a pull request can be merged.

Unleash's open source edition is licensed under AGPL-3.0-or-later.