.XMLX File

The xmlx extension is sometimes used for common Microsoft Excel xlsx spreadsheet.

Excel is a part of Microsoft Office suite for Windows and Mac.

Probably just renamed so it is not associated with Microsoft Excel by default.

This xmlx file type entry was marked as obsolete and no longer supported file format.

This type of file is no longer actively used and is most likely obsolete. This is typically the case for system files in old operating systems, file types from long discontinued software, or previous versions of certain file types (like documents, projects etc.) that were replaced in higher versions of their original programs.

How to open:

Rename the file to XLSX and open it with Microsoft Excel.

How to convert:

Use compatible tools to export *.xmlx files to other formats.