Deploy Anywhere and Own Your Releases with Open-Source Feature Flags
Full transparency, no vendor lock-in—Flagsmith is the feature flag platform built in public and kept that way.
Trusted by top development teams
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BSD-3-Clause licence
One of the most permissive open-source licences available—no restrictions on commercial use.
Core will always be open
Flags, segments, user targeting, and remote configuration. Always free, always open.
Compatible with OpenFeature
Stay vendor-agnostic. Switch tools without rewriting your existing development workflows.
Most open-source tools aren’t as open as they claim
The “open source” label gets stretched. Many tools keep core functionality behind Enterprise plans or switch to restrictive licences as they scale.
Flagsmith is different. We’re committed to open source.
Core functionality—feature flags, remote configuration, user targeting, multivariate flags, and targeting rules—is BSD-3-Clause licensed, free to use in production, and available to inspect, fork, and self-host without restriction.
Our open source licensing and ethos
The vast majority of our platform is open source. View our GitHub.
Most of our platform is under the BSD-3-Clause license. A small number of repositories are under the MIT license.
We built Flagsmith as the open source feature flagging platform we needed but couldn't find on GitHub. Our core functionality stays open, always. Read our open letter to developers.
Use cases for open source feature flags
Decouple deploy and release
Achieve continuous deployment by deploying behind flags, and then only toggling them on when a release is scheduled.
Canary Deployments
Using Flagsmith, you can release new features to a small percentage of your users initially, and then enable them for the rest of your users over time.
A/B/n Testing
Once you’ve integrated the Flagsmith SDK and gated a feature with a flag, you can then easily use that flag to power A/B/n tests.
“We decided on Flagsmith not just because of the system’s flexibility, but also the great support, the fact that you guys are open source and the great documentation.” - Jindrich Kubat, Head of Development, Komerční Banka
SDKs & frameworks
Choose from 15+ popular languages like Typescript, .NET, Java, and more
Integrate with any framework, including React, Next.js, and more
Or choose to remain vendor-agnostic with OpenFeature’s open source SDKs and frameworks
Our core functionality stays open. This means you can use open-source feature flags and feature management no matter what. Several of our enterprise-level management features are not open source, but they are source available. Read more about our build decisions here.
Yes! We have a robust community of contributors. Here are our guidelines for contributing to open source feature flags. If you have any questions about your contribution, you can also chat with us on Discord.
Our core feature flag functionality is open source (flags, segments, identities, etc.). Enterprise-level governance and management features are not open source, however. They are available on open source, but to use them in production we require that you have a valid Flagsmith Enterprise license.
An open source feature flag is a toggle that allows developers to enable or disable features in their applications without deploying new code. You can inspect the source code, modify it to fit your needs, and avoid vendor lock-in while still getting enterprise-grade feature management capabilities.
Flagsmith's core feature flag functionality is completely open source, including flags, segments, identities, and basic feature management. However, some enterprise-level governance and management features are paid rather than fully open source.
Open source feature flagging solutions are better because:
° You get complete transparency into how your feature management works
° You can contribute improvements and fixes to the product
° You’re not locked into a contract you don’t want (or need) anymore
° You get full control over your data and can customise the platform as needed
OpenFeature is an open specification that offers a vendor-agnostic, community-driven API for feature flagging that works with feature flag management tools (like Flagsmith) or in-house solutions. We're proud to partner with OpenFeature and offer OpenFeature providers to prevent vendor lock-in at the code level.
