Unauthenticated callers

An unauthenticated caller is a user or service who provides no authentication information. Unauthenticated callers can access only metadata endpoints. Unauthenticated callers are typically callers who need information about Cloud API endpoints only.

This topic describes how to implement Cloud API authentication for unauthenticated callers.

Note: Anonymous users start out as unauthenticated callers. This topic focuses on unauthenticated callers who remain unauthenticated and who request Cloud API metadata only. For more information about anonymous users, see OAuth2 authorization code flow: Anonymous users.