A service running on a server, for example as a cloud server, that services with a guarantee from a guarantor. The service includes receiving, from a user using a zero-knowledge protocol to ensure privacy of the user, a request for a service with an associated quality level for a fee. Next, the request for service received requires a guarantee of the service requiring additional assurances based on a rating quantity available by a guarantor of the service is identified. At least a portion of the rating quantity available by the guarantor of the service is received. A notification from the user that the service is unacceptable is received. In response to the notification and a verification that the associated quality level was not met, refunding at least a portion of the fee to the user from the guarantor of the service.