Free Open Source IdentityServer, Forever.

If you’re here, you’re likely in one of two groups:

• You’re still running IdentityServer4 and looking for a supported path forward
• Or you’ve moved to Duende
• We understand both perspectives, because we’ve supported customers through both journeys.

Since 2016, we’ve been deeply involved in the IdentityServer ecosystem. From consultancy and production support, to building commercial extensions (with revenue shared back to support the open-source core team), we’ve seen first hand what made IdentityServer successful.

In 2022, when the platform became commercial under Duende, we made a conscious decision not to fork the project. Instead, we operated under an informal understanding: Duende would focus on licensing the core, and we would continue delivering complementary products.

Following Duende’s acquisition in 2024, we continued that partnership, working closely with their team and helping customers migrate successfully to Duende. However, in February 2026, that position changed, and products began to overlap more directly. At that point, Duende transitioned from a partner to a competitor, which forced us to act.

We have forked and updated IdentityServer4 and are maintaining it as a fully supported, free, open-source platform called Open.IdentityServer giving customers a genuine alternative to a paid license.

What this means for you

If you’re on IdentityServer4:

You now have an actively maintained free open-source path without needing to switch to a commercial license.

• Read our migration guide
• Watch an 8-minute video on how easy it is to migrate

If you’re on Duende:

You can evaluate whether a free, open-source alternative fits your long-term strategy.

• Read our migration guide
• Watch an 8-minute video  on how easy it is to migrate

If you're starting a new SSO solution

You can try one of our many quick starts and have an SSO solution up and running in no time. 

For everyone:

• The core identity platform is free of charge
• Commercial add-ons remain optional
• The model is designed for long-term sustainability

Trust and sustainability are critical when choosing an identity platform, so we’ve documented exactly how this works and how we intend to support keeping  Open IdentityServer free forever.

• Read our Manifesto to understand the model, the commitment, and the long-term vision
• Read our Roadmap
• Read the latest Release Notes

All our products remain compatible and fully supported with Open.IdentityServer, Duende IdentityServer and OpenIddict. Giving you free choice to use the Identity platform that is right for you.

Open.IdentityServer is an independent open‑source project led by Rock Solid Knowledge, based on the Apache 2.0‑licensed IdentityServer4 codebase. It is not affiliated with or endorsed by Duende Software or the original IdentityServer4 authors.