A DEF file is a data file created in spreadsheet file format by SmartWare II database application, developed by Informix Software. Software II had four modules including spreadsheet with graphics, word processor, communications, and database. The SmartWare II database is a standalone database that can be integrated with other applications as well. Queries can be executed on data that can be extracted and saved to the DEF file format. DEF spreadsheet files can be opened with SmartWare software which has been discontinued now.