Create a Custom Authentication Provider Plug-in

Out of the box, Salesforce supports several external authentication providers for single sign-on, including Facebook, Google, LinkedIn, and service providers that implement the OpenID Connect protocol. By creating a plug-in with Apex, you can add your own OAuth-based authentication provider. Your users can then use the SSO credentials they already use for non-Salesforce applications with your Salesforce orgs.

Before you create your Apex class, you create a custom metadata type record for your authentication provider. For details, see Create a Custom External Authentication Provider.