A reverse API system is provided wherein data retrieved from disparate data sources, including legacy information in obsolete formats, are standardized and combined. An interactive text editor software tool allows an administrator to compose or edit standardization schema that include data source formulas which identify the data locations and any needed access protocols and that also include standardization functions which define transformations and other data handling instructions whereby retrieved data is standardized, unified and optionally enhanced by the system prior to delivery to a requestor. Requestors invoke the composed schema stored in a library, which invocation then triggers the retrieval and standardization of the data by the system executing the data source formulas and standardization functions associated with that selected schema.