Device, computer program product and method for checking properties of resources, wherein a checking device for checking properties of resources of a web server includes a calculation unit for calculating an identifier identifying a particular resource using the particular resource, a detection unit for detecting a license requirement for the particular resource using the calculated identifier, and a determination unit for determining an existing license for the web server in the case of a license requirement detected for the particular resource using the calculated identifier, such that unauthorized posting of a particular resource to a web server can be easily detected and prevented.