4th Dimension (or 4D) is a relational database management system developed by Laurent Ribardiere in 1984. In 1993, 4D Server, the client/server version of 4th Dimension was introduced and since 1995, 4D has supported both the Microsoft Windows and Apple Macintosh operating systems.

The 4D product line has since expanded to an SQL front-end and several productivity plug-ins and interfaces.

Today, 4D is maintained by the France company 4D SA.

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