Welcome to IdentityServer4 (latest)ΒΆ


IdentityServer4 is an OpenID Connect and OAuth 2.0 framework for ASP.NET Core.


As of Oct, 1st 2020, we started a new company. All new development will happen in our new organization. The new Duende IdentityServer is free for dev/testing/personal projects and companies or individuals with less than 1M USD gross annual revenue - for all others we have various commercial licenses that also include support and updates. Contact us for more information.

IdentityServer4 will be maintained with security updates until November 2022.


This docs cover the latest version on main branch. This might not be released yet. Use the version picker in the lower left corner to select docs for a specific version.

It enables the following features in your applications:

Authentication as a Service
Centralized login logic and workflow for all of your applications (web, native, mobile, services). IdentityServer is an officially certified implementation of OpenID Connect.
Single Sign-on / Sign-out
Single sign-on (and out) over multiple application types.
Access Control for APIs
Issue access tokens for APIs for various types of clients, e.g. server to server, web applications, SPAs and native/mobile apps.
Federation Gateway
Support for external identity providers like Azure Active Directory, Google, Facebook etc. This shields your applications from the details of how to connect to these external providers.
Focus on Customization
The most important part - many aspects of IdentityServer can be customized to fit your needs. Since IdentityServer is a framework and not a boxed product or a SaaS, you can write code to adapt the system the way it makes sense for your scenarios.
Mature Open Source
IdentityServer uses the permissive Apache 2 license that allows building commercial products on top of it. It is also part of the .NET Foundation which provides governance and legal backing.
Free and Commercial Support
If you need help building or running your identity platform, let us know. There are several ways we can help you out.