[opensourcedex]

Unleash is a free, open source application security project written in TypeScript and released under AGPL-3.0. It has 13,811 GitHub stars, 896 forks and 39 open issues, and was last pushed 18 hours ago. On this registry it ranks #2 of 16 tracked projects in Application Security, with 5 head-to-head comparisons available. It gained 8 stars over the last 6 tracked days.

Unleash — Feature flags for rapid, risk-free software deployment

What is Unleash?

What it is

Unleash is an open-source feature management platform written in TypeScript and released under the AGPL-3.0 license. It lives in the DevOps, continuous-delivery, and application-security ecosystem, and its topics describe feature flags, feature toggles, activation strategies, experiments, and collaboration.

The concrete problem it solves is the risk of releasing large code changes directly to end users. Unleash lets teams deploy code to production in smaller, manageable releases and control how and when new features are rolled out. Feature flags allow teams to test code with real production data, reduce the risk of negatively impacting users, and work on multiple features without separate feature branches.

Key capabilities

  • Feature flags and feature toggles let teams control how and when new features are rolled out to end users.
  • Unleash supports testing code with real production data, which reduces the risk of negatively impacting the user experience.
  • The project supports 15 official client and server SDKs and over 15 community SDKs, and it is compatible with any language and framework.
  • The topic list identifies activation strategies and experiments as supported capabilities.
  • The topic list identifies continuous delivery, continuous deployment, DevOps, and collaboration as supported workflow areas.

Who uses it and how

  • Teams use Unleash to deploy code to production in smaller, manageable releases at their own pace.
  • Teams use feature flags to test code with real production data while reducing the risk of negatively impacting users.
  • Teams can use Unleash to work on multiple features without separate feature branches.
  • Organizations can use Unleash Enterprise for a hosted instance with unlimited projects and environments, role-based access control, change requests, single sign-on, and SCIM.
  • Developers can connect frontend SDKs to http://localhost:4242/api/frontend/ and backend SDKs to http://localhost:4242/api/ with the tokens shown in the README.

Getting started

To run the open-source server locally, users need git and docker, then clone the repository, run docker compose up -d, and open localhost:4242 with username admin and password unleash4all; the README also describes running the source code via Node.js. The README references the Docker image unleashorg/unleash-server and a hosted Unleash Enterprise free-trial option.

When to use it — and when not to

Unleash is suitable when teams want open-source feature flags and local Docker Compose control, while Unleash Enterprise provides a hosted instance with unlimited projects and environments, role-based access control, change requests, single sign-on, and SCIM. Self-hosters must operate the local Docker Compose setup and configure SDK endpoints and tokens; the README excerpt does not specify database, storage, or SMTP requirements. The metadata lists 0 contributors and a repo age of 0 years, which is a weakness for assessing maturity.

project readme (upstream, from github) — read inline


Build and Tests Coverage Report Docker Pulls AGPL-3.0-or-later license Join Unleash on Slack

Launch the live demo | Try Unleash Enterprise for free

What is Unleash?

Unleash is a powerful open-source solution for feature management. It streamlines your development workflow, accelerates software delivery, and empowers teams to control how and when they roll out new features to end users. With Unleash, you can deploy code to production in smaller, more manageable releases at your own pace.

Feature flags in Unleash let you test your code with real production data, reducing the risk of negatively impacting your users' experience. It also enables your team to work on multiple features simultaneously without the need for separate feature branches.

Unleash is the most popular open-source solution for feature flagging on GitHub. It supports 15 official client and server SDKs and over 15 community SDKs. You can even create your own SDK if you wish. Unleash is compatible with any language and framework.


Get started with Unleash

Set up Unleash

To get started with Unleash, you can either explore Unleash Enterprise with a free trial or get started locally with our open-source solution.

Unleash Enterprise

To start with Unleash Enterprise, request a free trial. This gives you access to a hosted instance with unlimited projects and environments and features such as role-based access control, change requests, single sign-on, and SCIM for automatic user provisioning.

Unleash Open Source

To set up Unleash locally, you'll need git and docker installed on your machine.

Execute the following commands:

git clone [email protected]:Unleash/unleash.git
cd unleash
docker compose up -d

Then point your browser to localhost:4242 and log in using:

  • username: admin
  • password: unleash4all

If you'd rather run the source code in this repo directly via Node.js, see the step-by-step instructions to get up and running in the contributing guide.

Connect your SDK

Find your preferred SDK in our list of official SDKs and import it into your project. Follow the setup guides for your specific SDK.

If you use the docker compose file from the previous step, here's the configuration details you'll need to get going:

  • For frontend SDKs, use:
    • URL: http://localhost:4242/api/frontend/
    • clientKey: default:development.unleash-insecure-frontend-api-token
  • For backend SDKs, use:
    • Unleash API URL: http://localhost:4242/api/
    • API token: default:development.unleash-insecure-api-token

If you use a different setup, your configuration details will most likely also be different.

Check a feature flag

Checking the state of a feature flag in your code is easy! The syntax will vary depending on your language, but all you need is a simple function call to check whether a flag is available. Here's how it might look in Java:

if (unleash.isEnabled("AwesomeFeature")) {
  // do new, flashy thing
} else {
  // do old, boring stuff
}

Try Unleash in the cloud

Want to explore Unleash without setting it up locally? Here are two easy ways to see it in action.

Live demo

Open a running Unleash environment in your browser with no signup or setup required. This shared demo instance includes the core functionality so you can quickly get a feel for how Unleash works.

→ Launch the live demo

Launch the live demo

Free Enterprise trial

Get your own dedicated instance with a free 14-day cloud trial. This includes the full Unleash Enterprise feature set; ideal when evaluating Unleash for production use.

→ Start your free trial


Deploying to a production server

To self-host Unleash in a production environment, you need to deploy it to a persistent server.

We provide guides for deploying to services like Heroku and DigitalOcean:

Deploy to Heroku Deploy to DigitalOcean

For more advanced configurations options, check out our documentation on:


Community and help

We know that learning a new tool can be hard and time-consuming. We have a growing community that loves to help out. Please don't hesitate to reach out for help.

Join Unleash on Slack

💬 Join Unleash on Slack if you want ask open questions about Unleash, feature toggling or discuss these topics in general.

💻 Create a GitHub issue if you have found a bug or have ideas on how to improve Unleash.

📚 Visit the documentation for more in-depth descriptions, how-to guides, and more.

📖 Learn more about the principles of building and scaling feature flag solutions.


Contribute to Unleash

Unleash is the largest open-source feature flag solution on GitHub. Building Unleash is a collaborative effort, and we owe a lot of gratitude to many smart and talented individuals. Building it together with the community ensures that we build a product that solves real problems for real people. We'd love to have your help too: Please feel free to open issues or provide pull requests.

Check out the CONTRIBUTING.md file for contribution guidelines and the Unleash developer guide for tips on environment setup, running the tests, and running Unleash from source. Before a pull request can be merged, contributors must read and agree to the Unleash Contributor License Agreement.

Contributors

The Unleash contributors


Documentation

You can visit the Unleash documentation at https://docs.getunleash.io. As of 2 February 2026, the Unleash documentation source code lives in its own repository: Unleash/unleash-documentation.

Features our users love

Flexibility and adaptability

readme truncated — read the full docs on github

Frequently asked questions

Is Unleash free to use?

Unleash is open source under the AGPL-3.0 licence. There is no licence fee and no seat count — you can self-host it or, where the project offers one, pay a vendor for a managed version instead.

What does Unleash do?

Feature flags for rapid, risk-free software deployment

What is Unleash written in?

Unleash is primarily written in TypeScript. Its source is publicly available at https://github.com/unleash/unleash, and it has 13,811 GitHub stars.