What is an Authentication / Identity) Provider ? ie user store

About

An Authentication Provider implements the authentication method and is also known as an identity provider.

The providers implementation differs primarily by:

• the data store (ie user store) that is request.
• the methods that it implements

List

• Any social provider (such as facebook, twitter, google, …)
• or a specific application:
  • Weblogic - Authentication Provider
  • Aws - Cognito
  • https://docs.openstack.org/keystone/queens/
  • keycloack (Java based)
  • Auth0
  • Okta
  • Firebase Auth
  • https://supertokens.io/
  • …
• or a HTTP middelware (ie handler)
  • http://www.passportjs.org - authentication middleware for Node
  • https://vertx.io/docs/vertx-auth-common/java/

They may supports:

• oauth (ie they are oauth provider in the oauth sequence)
• LDAP