A method and apparatus for processing metadata search with plug-in applications is disclosed. In one embodiment, in response to a search request for metadata stored in a metadata store, a plug-in associated with the metadata store is invoked to perform the request search within the metadata store. In addition, according to another embodiment, a search result of the metadata search may be filtered based on user privileges of a client initiating the search request, and some or all of the metadata from the search result may be returned to the client dependent upon the user privileges of the client. Other methods and apparatuses are also described.