# Unleash — Feature Management Platform

> Unleash is an open-source feature management platform designed for large enterprises that helps software teams manage feature flags, run A/B tests, and deliver software faster with full control over feature rollouts and compliance.

## What is Unleash?

Unleash is the most popular open-source feature flagging and feature management solution for enterprises. It allows development teams to decouple code deployments from feature releases, enabling practices like trunk-based development, progressive delivery, canary releases, and blue-green deployments.

Unleash was created in 2015 and is recommended by ThoughtWorks Technology Radar. It is rated the easiest to use on G2 among feature flag tools.

The platform is available in two forms:

1. **Open Source** (self-hosted, free forever): Full-featured feature flag server that can be deployed via Docker, Kubernetes (Helm charts), or any Node.js environment. Source code at github.com/Unleash/unleash.

2. **Commercial** (cloud-hosted or self-hosted): Adds enterprise capabilities including SSO, RBAC, audit logs, change requests, A/B testing, and compliance certifications. Available as pay-as-you-go ($75/seat/month) or custom enterprise pricing.

## Core Capabilities

### Feature Flags
Unleash provides a robust feature flag system that supports multiple activation strategies out of the box:
- **Gradual rollout**: Release features to a percentage of users, increasing over time.
- **User targeting**: Target specific users by user ID, email, or any custom attribute.
- **IP-based targeting**: Enable features for specific IP ranges (useful for internal testing).
- **Custom strategies**: Define your own activation logic using the Strategy pattern.
- **Variants**: Assign different feature variants to users for A/B/n testing with payload support (string, JSON, number).
- **Constraints**: Add fine-grained rules to strategies based on context fields like country, app version, or subscription tier.
- **Segments**: Reusable groups of constraints that can be shared across flags and projects.
- **Dependent flags**: Create parent-child relationships between flags to model complex release dependencies.

### Feature Flag Lifecycle Management
Unleash tracks the full lifecycle of every feature flag from creation to cleanup:
- **Flag types**: Release, Experiment, Operational, Kill Switch, Permission — each with different expected lifetimes.
- **Stale flag detection**: Automatically identifies flags that have been active beyond their expected lifetime.
- **Potentially stale warnings**: Proactive alerts before flags become truly stale.
- **Impact metrics**: Track how each flag is being evaluated across environments with usage data.
- **Archive and cleanup**: Safely archive flags that are no longer needed, with dependency checks.

### A/B Testing and Experimentation
Unleash supports A/B/n testing through its variants system:
- Define multiple variants per feature flag with percentage-based weight distribution.
- Attach payloads to variants (strings, JSON objects, numbers) for dynamic configuration.
- Sticky assignment ensures users consistently see the same variant across sessions.
- Statistical analysis support through integration with external analytics tools.
- Works with any analytics platform via SDK impression events.

### Change Requests and Approval Workflows
Enterprise feature for governance and compliance:
- **Four-eyes principle**: Require peer approval before changes go live.
- **Per-environment configuration**: Different approval rules per environment (e.g., stricter for production).
- **Audit trail**: Full history of who requested, reviewed, and approved every change.
- **Scheduled changes**: Plan flag changes for a future date/time.
- **Conflict detection**: Warns when multiple pending change requests affect the same flag.

### Projects and Environments
Organize feature flags at scale:
- **Projects**: Group related flags by team, product, or domain. Each project has its own members, roles, and settings.
- **Environments**: Model your deployment pipeline (development, staging, production). Each flag can be independently configured per environment.
- **Unlimited flags, projects, and environments** on commercial plans. The open-source edition is limited to a single project.

### Role-Based Access Control (RBAC)
Fine-grained permission system:
- **Predefined roles**: Admin, Editor, Viewer at global and project levels.
- **Custom project roles**: Create roles tailored to your organization's access patterns.
- **Project-level permissions**: Control who can create, update, approve, or delete flags within each project.
- **API token scoping**: Tokens are scoped to specific projects and environments.
- **Groups**: Organize users into groups synced with your identity provider for easier management.

### Single Sign-On (SSO)
Enterprise authentication integrations:
- SAML 2.0
- OpenID Connect (OIDC)
- Azure Active Directory
- Okta
- Google Workspace
- Custom OIDC providers

## Architecture

### How Unleash Works
Unleash uses a client-server architecture optimized for performance and reliability:

1. **Unleash Server**: Central API that stores flag configurations in PostgreSQL. Provides Admin API (for management), Client API (for SDKs), and Frontend API (for browser/mobile SDKs).

2. **Unleash SDKs**: Lightweight libraries that connect to the Unleash API, download flag configurations, and evaluate flags locally in your application's process. SDKs poll for updates (configurable interval, typically 15 seconds) and cache configurations in memory.

3. **Unleash Enterprise Edge**: An optional high-performance edge layer (written in Rust) that sits between your SDKs and the Unleash server. It caches flag evaluations close to your users for sub-millisecond response times, reduces load on the main server, and enables multi-region deployments.

### Key Architectural Properties
- **Local evaluation**: All flag evaluations happen in your application's process (server-side SDKs) or at the edge. No network call per flag check.
- **Resilience**: SDKs cache configurations locally. If Unleash server goes down, your application continues with the last known configuration.
- **Low latency**: Typical flag evaluation is sub-microsecond (server-side) or sub-millisecond (via Edge).
- **No PII in Unleash**: The Unleash server never sees your end users' data. Context attributes are evaluated locally by SDKs.

## SDKs

Unleash provides official SDKs for 25+ languages and frameworks. All SDKs are open-source.

### Server-Side SDKs
Server-side SDKs run in your backend services. They connect directly to the Unleash API (or Edge), download all flag configurations, and evaluate flags locally in-process.

- **Node.js**: github.com/Unleash/unleash-node-sdk
- **Java**: github.com/Unleash/unleash-java-sdk
- **Go**: github.com/Unleash/unleash-go-sdk
- **Python**: github.com/Unleash/unleash-python-sdk
- **.NET**: github.com/Unleash/unleash-dotnet-sdk
- **Ruby**: github.com/Unleash/unleash-ruby-sdk
- **PHP**: github.com/Unleash/unleash-php-sdk
- **Rust**: github.com/Unleash/unleash-rust-sdk
- **Symfony**: github.com/Unleash/unleash-client-symfony

### Client-Side SDKs
Client-side SDKs run in browsers or mobile apps. They connect to the Unleash Frontend API (or Edge) which evaluates flags server-side and returns only the results, ensuring flag configurations are never exposed to end users.

- **JavaScript (Browser)**: github.com/Unleash/unleash-js-sdk
- **React**: github.com/Unleash/unleash-react-sdk
- **Vue**: github.com/Unleash/unleash-vue-sdk
- **Svelte**: github.com/Unleash/unleash-svelte-sdk
- **Next.js**: github.com/Unleash/unleash-nextjs-sdk
- **React Native**: github.com/Unleash/unleash-react-native-sdk
- **Android**: github.com/Unleash/unleash-android-sdk
- **iOS**: github.com/Unleash/unleash-ios-sdk
- **Flutter**: github.com/Unleash/unleash-flutter-sdk

### Unleash Enterprise Edge
Unleash Enterprise Edge is a high-performance, stateless proxy written in Rust:
- Sub-millisecond flag evaluation at the edge
- Horizontal scaling for millions of connected clients
- Multi-region deployment support
- Works as a replacement for the deprecated Unleash Proxy
- Documentation: docs.getunleash.io/unleash-edge

## Integrations

Unleash integrates with the tools your team already uses:

- **Slack**: Real-time notifications for flag changes, approvals, and lifecycle events.
- **Microsoft Teams**: Same notification capabilities as Slack.
- **Datadog**: Feature flag tracking alongside your application metrics and traces.
- **Jira**: Link feature flags to Jira issues for traceability.
- **Terraform**: Manage Unleash resources (projects, flags, environments) as infrastructure-as-code. Provider: github.com/Unleash/terraform-provider-unleash
- **GitHub Copilot**: AI-assisted feature flag management through Copilot Extensions.
- **Claude Code**: MCP server integration for AI-assisted feature flag management through Anthropic's Claude.
- **Kiro**: AI-assisted and spec-driven development workflows through Amazon's Kiro IDE and CLI.

## Pricing

### Open Source (Free)
- Self-hosted via Docker or Kubernetes
- Unlimited feature flags
- Core activation strategies
- API and basic UI
- Community support
- Source: github.com/Unleash/unleash
- Docker: hub.docker.com/r/unleashorg/unleash-server
- Helm: github.com/Unleash/helm-charts

### Pay-as-you-go — Cloud ($75/seat/month)
- Everything in Open Source, plus:
- Managed cloud hosting (99.9% uptime SLA)
- A/B/n testing with variants
- Change request workflows
- SSO (SAML 2.0, OIDC)
- Role-based access control with custom roles
- Feature flag lifecycle management
- Audit logs
- Impact metrics
- 25+ official SDKs with premium support
- 14-day free trial, no credit card required
- Sign up: getunleash.io/plans/enterprise-payg

### Pay-as-you-go — Self-hosted ($75/seat/month, 5-seat minimum)
- Same features as Cloud pay-as-you-go
- Deployed in your own infrastructure
- Full data control and sovereignty

### Enterprise (Custom pricing)
- Everything in pay-as-you-go, plus:
- 99.99% uptime SLA
- Private cloud instances
- Multi-region Edge deployment
- IP-based access restrictions
- Dedicated customer success manager
- Guided onboarding
- Premium support with SLAs
- Custom contracts and invoicing
- Contact sales: getunleash.io/plans/enterprise

## Compliance and Security

- **SOC 2 Type II certified**: Annual audits by independent third parties.
- **GDPR compliant**: No PII stored on Unleash servers. All flag evaluation happens locally in SDKs. Data Processing Agreement available.
- **FedRAMP**: Available for US government customers (Enterprise plan).
- **Data residency**: Choose where your data is stored (US, EU, or custom regions on Enterprise).
- **Encryption**: All data encrypted at rest and in transit.
- **Audit logs**: Complete audit trail of every change, accessible via API and UI.
- **API token security**: Tokens scoped by project and environment, rotatable without downtime.
- Privacy and compliance details: docs.getunleash.io/privacy-and-compliance

## Deployment Options

1. **Cloud-hosted**: Fully managed by Unleash. No infrastructure to maintain. Available in multiple regions.
2. **Self-hosted (Docker)**: Run the official Docker image in your own infrastructure. `docker pull unleashorg/unleash-server`
3. **Self-hosted (Kubernetes)**: Deploy using official Helm charts for production-grade Kubernetes deployments.
4. **Hybrid**: Use Unleash Edge at the edge of your infrastructure while connecting to cloud-hosted or self-hosted Unleash server.

## Use Cases

### Trunk-Based Development
Use feature flags to merge incomplete features into the main branch safely. Flags keep unfinished work hidden from users while allowing continuous integration. This eliminates long-lived feature branches and reduces merge conflicts.

### Progressive Delivery
Release features gradually to increasing percentages of users. Start with internal users (dogfooding), expand to beta testers, then progressively roll out to all users. Unleash's gradual rollout strategy with stickiness ensures consistent user experience during rollouts.

### Kill Switches
Instantly disable problematic features in production without deploying new code. Operational flags can serve as circuit breakers for external dependencies, turning off functionality that relies on a degraded third-party service.

### A/B Testing
Use Unleash variants to test multiple versions of a feature with real users. Assign variants with custom payloads, track results through your analytics platform via impression events, and make data-driven decisions about which version to ship.

### Compliance and Governance
Change request workflows enforce four-eyes approval before production changes. Combined with audit logs and RBAC, this provides the governance framework required by regulated industries (banking, healthcare, government).

### Multi-Environment Management
Model your deployment pipeline with separate environments. Configure each flag independently per environment — a flag can be enabled in staging for QA while remaining disabled in production until approved.

## Customer Case Studies

Unleash is used by thousands of organizations, from startups to Fortune 500 companies:

- **Lloyds Banking Group**: Feature management at scale for one of the UK's largest financial institutions.
- **Mercadona**: Spain's largest supermarket chain uses Unleash for digital transformation.
- **Prudential**: Global insurance and financial services company.
- **Wayfair**: E-commerce platform managing feature releases across multiple teams.
- **Visa**: Global payments technology company.

More case studies: getunleash.io/case-studies

## Documentation and Learning

- **Quickstart guide**: docs.getunleash.io/get-started/quickstart
- **Core concepts**: docs.getunleash.io/get-started/what-is-a-feature-flag
- **Architecture overview**: docs.getunleash.io/get-started/unleash-overview
- **SDK documentation**: docs.getunleash.io/sdks
- **API reference**: docs.getunleash.io/api (Admin, Client, and Frontend APIs)
- **Integrations guide**: docs.getunleash.io/integrate
- **Deployment options**: docs.getunleash.io/deploy/hosting-options
- **Unleash Enterprise Edge**: docs.getunleash.io/unleash-edge
- **Tutorials and guides**: docs.getunleash.io/guides
- **Release notes**: docs.getunleash.io/release-notes
- **Unleash Academy** (free certifications): docs.getunleash.io/unleash-academy/introduction

## FeatureOps

Unleash coined the term FeatureOps to describe the practice of connecting engineering performance to business outcomes through systematic feature management. FeatureOps encompasses the processes, tools, and culture around managing the full lifecycle of feature flags — from creation through rollout to cleanup.

Read the FeatureOps whitepaper: cdn.getunleash.io/uploads/2025/03/FeatureOps-whitepaper.pdf
Learn more at: featureops.io

## Community and Open Source

- **GitHub**: github.com/Unleash/unleash (star the repo to show support)
- **Docker Hub**: hub.docker.com/r/unleashorg/unleash-server
- **Helm Charts**: github.com/Unleash/helm-charts
- **Terraform Provider**: github.com/Unleash/terraform-provider-unleash
- **LinkedIn**: linkedin.com/company/getunleash/
- **X / Twitter**: x.com/getunleash
- **YouTube**: youtube.com/channel/UCJjGVOc5QBbEje-r7nZEa4A

## Contact

- **Website**: getunleash.io
- **Book a demo**: getunleash.io/plans/enterprise
- **Start free trial**: getunleash.io/plans/enterprise-payg
- **Documentation**: docs.getunleash.io
- **Live demo instance**: app.unleash-hosted.com/demo/login
- **Careers**: getunleash.io/careers