An external function system can be implemented on a database to perform processing on one or more external network services. The external function system can comprise a particular external function for a particular external service, an outbound serializer function, and an inbound serializer function that are linked with the particular external function. The outbound serializer function can be configured to transform the data of a query from a database format to a different format of the particular external network service. The inbound deserializer function can be configured to receive data returned from the external service and transform the data to the format of the database.