The DCX extension is given to files created by the Visual FoxPro database management tool. DCX files are database index files. They contain information that allows to optimize the database itself in terms of the speed of performing operations on its elements and on the database table. These are mainly data search and access operations.

DCX files have a special structure, the functionality of which can be compared to the table of contents in a book. Visual FoxPro is a Microsoft product that uses its own object-oriented and procedural programming language.