Welcome to IdentityServer4

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

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).

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 Directoy, Google, Facebook etc. This shields your applicatios from the details of how to connect to these external providers.

Focus on Customization

The most important part - many aspect 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.