The described technology is directed towards locating and using a template for processing data item data from a general form into a client-specific form for returning in response to a client request. A client request includes a data item identifier and client-specific information. The data item's identifier is processed into a data type and/or identifier, e.g., a string. The client-specific information is used to determine a device class, device type and/or client platform software version. The template is found in a hierarchy of templates based upon the client-specific information and the data type or data ID string, e.g., the client-specific information may be used to determine a subset of template folders that is evaluated to find a file with a filename matching the string. The folders may be ordered from most-specific to least-specific, so as to locate the most specific template file that applies.