In order to compare cloud-based signing solutions with conventional, paper-based signatures we reviewed seven representative examples of cloud-based signature services and assessed them with respect to the provided cryptographic features, the interfaces they offer, the authentication methods they provide and the key storage implementations used. The combination of cloud-based signing solutions and cloud storage infrastructures promises faster process flows for signing a contract than the classic paper-based approach. We found that multi-factor authentication and hardware security module back-ends are common features. Interfaces range from APIs over web user interfaces to proprietary applications. Yet, there are shortcomings in flexibility and security.