4D is a relational DBMS that is integrated with an IDE and a proprietary programming language. It allows users to create custom graphical interfaces to work with their database, which can then be run on Windows or Mac OS systems to edit a locally stored database file. 4D can also run as a server so that multiple clients can manage a single database. The latest version of 4D includes "4D for iOS Preview" which creates a customizable iOS app for viewing database contents.