Using IdentityServer as your identity provider provides many benefits out of the box. This, combined with it's high degree of customizability, makes it the leading OpenID Connect Identity Provider available.
IdentityServer is completely open source with no complex agreements to sign or subscriptions to pay. IdentityServer is developed to the OpenID Connect specification ensuring platform agnostic integration with no implementation specific requirements.
IdentityServer comes with Single Sign On (SSO) out of the box. This is not only a user experience boon, with users only needing to log in to your brand's identity provider, but it also means that you only need to implement your authentication logic once.
Implementing both OpenID Connect and OAuth, IdentityServer can provide security for your sensitive internal resources, delegating and scoping access based on the requesting user or application.
IdentityServer is fully compatible with all mobile devices, with existing libraries available that make Xamarin integration simple, and offer support for Proof-of-Possession tokens.