INX is a file that contains the code for the universal XML markup. It can be opened by any text editor. INX files are used by Adobe InDesign. They contain data that allows the correct exchange of files between different versions of this software. This is information about the file structure: e.g. the number of pages, their layout and content.

The INX format is supported by the Adobe InDesign Interchange tool. InDesign is a program that is a component of Adobe Creative Cloud.