Sign in with Apple REST API
Sign in with Apple is Apple's OpenID Connect-style identity provider for iOS, web, and other Apple-platform apps. The REST surface, hosted at appleid.apple.com, exposes /auth/token (authorization-code and refresh- token exchange), /auth/revoke (token revocation), /auth/keys (JWKS public keys for ID-token validation), and a server-to-server notification channel for account-deletion and email-relay events. Required for any iOS app offering third-party social login.