1. A method to provide support for custom file types in a web application environment, the method comprising: registering a file handler application with a directory service associated with the web application environment; declaring a file handler manifest comprising a file handler application property upon registration of the file handler application; detecting a non-native file within the web application environment; responsive to a determination that the file handler application supports a type of the non-native file, retrieving metadata associated with the non-native file by making a request to a URL specified in the file handler application property to point to a method in the file handler application configured to retrieve a file stream for the non-native file; generating a preview associated with the non-native file based on the file stream retrieved; and displaying the preview and the metadata along with the non-native file.