Experimentation & feature flags · Unleash

Unleash

Open-source feature-flag platform with rollout-based experimentation, moved from Apache-2.0 to AGPLv3 licensing in mid-2026.

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Unleash is primarily a feature-flag management system — targeting rules, gradual rollouts, and kill switches across 25+ SDKs — with experimentation layered on top of flagged traffic rather than warehouse-native statistical analysis. Like other flag-first platforms, it measures impact from its own SDK/API telemetry rather than a customer's warehouse tables. As of Unleash v8 (June 2026), the source in its main GitHub repository moved from the permissive Apache-2.0 license to AGPLv3, meaning a modified version made available over a network must also be open-sourced under AGPLv3 or licensed commercially; official Docker images and SDKs remain under their prior permissive licenses. It can be self-hosted for free or run on Unleash's managed cloud, with paid plans required beyond a single project/environment.

At a glance

Vendor Unleash
Pricing model Free tier + paid plans
Free tier Yes
Deployment Cloud, Self-hosted
Open source Yes (AGPL-3.0)
Best for Engineering teams wanting an open-source flagging system with basic rollout experimentation, self-hostable under AGPLv3.

Pricing

Free self-hosted open source (1 project, 2 environments, 5,000 flags); Pay-As-You-Go cloud is $75/seat/month; Enterprise is custom.

Plan Price Notes
Open Source $0 self-hosted, 1 project, 2 environments, 5,000 feature flags per instance
Pay-As-You-Go $75/seat/month cloud-hosted, 5-seat minimum, 53M API requests/month included
Enterprise custom cloud, self-hosted, or hybrid; annual contract

Prices read from the vendor's own page on September 21, 2026. Vendors change prices; check the source before you budget.

Features

  • Feature flags with targeting rules and gradual rollouts
  • Rollout-based experimentation on flagged traffic
  • 25+ official SDKs
  • Self-hosted (AGPLv3) or managed cloud
  • Multi-region edge and private-instance add-ons
  • Unlimited flags, projects, and experiments on paid plans

Integrations

Profile last reviewed September 21, 2026

Alternatives

Flagsmith Open-source (BSD-3-Clause) feature-flag and remote-config platform with basic A/B testing on flagged traffic, self-hostable or cloud. LaunchDarkly Feature-flag management platform that also runs experiments on flagged rollouts, reading event data it collects itself rather than the warehouse. Harness Feature Management & Experimentation (formerly Split) Feature-flag platform with built-in statistical experimentation, acquired by Harness and sold as an Enterprise-plan module (Harness FME).

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Terms to know

A/B testing A controlled experiment that compares two variants to measure which one produces a better outcome.

Related guides

How to choose an experimentation and feature-flag platform Pick by where your experiment data comes from — flag telemetry or your own warehouse — and which statistical engine your team trusts, not feature count.