Unleash

What is Unleash?

Unleash is an open source feature flag and feature management platform. You wrap code in flags to turn functionality on or off at runtime — no redeploy — then use activation strategies to roll a feature out gradually, target specific users or segments, or kill it instantly if something breaks. It ships as a self-hostable server plus SDKs for your apps.

What is Unleash best for?

Engineering teams that want production feature flags on their own infrastructure, with the flag decisions kept private. It fits organizations with security or compliance needs — end-user data stays inside your application rather than being sent to a vendor — and teams practicing trunk-based development who ship unfinished work safely behind flags.

What can Unleash do?

• Toggle features at runtime and roll them out gradually with percentage-based and targeted activation strategies
• Target users by segment, context field, or custom constraints, and run A/B tests with sticky variants
• Use kill switches to disable a feature in real time during an incident
• Evaluate flags close to your apps with official SDKs for Go, Java, Node.js, PHP, Python, Ruby, Rust, and .NET, plus frontend SDKs (JavaScript, React, iOS, Android, Flutter, and more)
• Keep flag evaluation fast and private with Unleash Edge, so end-user data never leaves your infrastructure
• Automate everything through an API-first design, with audit logging and change management in paid tiers

Is Unleash free?

Partly — Unleash is open-core. The open source edition is genuinely free to self-host under AGPL-3.0 and covers core flagging, gradual rollouts, and the SDKs, but it’s capped at two environments. Team features like role-based access control, SSO, change-request approvals, and more environments live in the paid Pro and Enterprise tiers. Pay-as-you-go pricing starts around $75 per seat per month, with custom Enterprise pricing above that.

Where does Unleash fall short?

• It’s open-core, so several team and governance features are gated. The free self-hosted edition is limited to two environments; RBAC, SSO, change-request workflows, and advanced segmentation require a paid Pro or Enterprise plan.
• It’s flags-first, not a full experimentation suite. You get A/B variants, but there’s no built-in statistics engine to measure experiment significance — if experiment analysis against your own data warehouse matters, GrowthBook is a closer fit.
• Flag changes reach clients by polling on an interval, so updates take effect within seconds rather than the instant streaming push some hosted vendors use. Adding Unleash Edge tightens this, but it’s more moving parts to run.

What does Unleash replace?

Unleash is a self-hosted alternative to LaunchDarkly and Split. It does the same feature-management job — flags, targeting, gradual rollouts, kill switches — but you run it on your own infrastructure, keep end-user data in-house, and avoid per-seat SaaS pricing on the open source edition.

FAQ

Is Unleash open source? Yes. The Unleash server is licensed under AGPL-3.0, an OSI-approved open source license, and the code is public on GitHub. The paid Pro and Enterprise editions add proprietary features on top.

Can I self-host Unleash for free? Yes. The open source edition is free to self-host and includes the core flagging engine and SDKs. You only pay if you need paid-tier features like extra environments, SSO, or RBAC.

Is Unleash a good LaunchDarkly alternative? For teams that want self-hosting, data privacy, and no per-seat pricing, yes. LaunchDarkly offers deeper built-in experimentation and streaming updates out of the box, so weigh that against the control you gain by running Unleash yourself.

What do I need to run Unleash? A server that can run the Node.js app (Docker images are provided) and a PostgreSQL database for storage. From there you connect your applications using the language SDKs.