CUIX File

What are CUIX files and how to open them

Are you having problems opening a CUIX file or are you simply curious about its contents? We're here to explain the properties of these files and provide you with software that can open or handle your CUIX files.

What is a CUIX file?

A .CUIX file is an AutoCAD Custom User Interface file.

AutoCAD Custom User Interface format files are used to define how the software's menus, toolbars, ribbon tabs, workspaces, keyboard shortcuts and other interface elements are arranged and displayed. These files are produced by AutoCAD when using the Customize User Interface Editor (via the CUI command), or generated as part of enterprise or partial customizations. They let administrators or users customize the main interface or add new UI elements without altering the core installed layout.

These files are edited and loaded inside AutoCAD. The main customization file is loaded automatically when AutoCAD starts; an enterprise customization file may optionally be applied across many users to enforce standard settings. Partial customization files let users or plug-ins add specific interface elements like custom ribbons or toolbars. For migrating between releases, importing legacy customization (CUI, MNS, MNU, etc.) is done via the Transfer tab. Some resource images may be stored externally for different interface themes (light/dark).

Inside, the format is a ZIP-based package containing multiple XML files and custom image assets. It includes files like HEADER.CUIPK, MENU_PACKAGE_INFO.XMLPK, MENUGROUP.CUIPK, and others, and folders such as _RELS or Content_Types to structure the internal parts. The file begins with the signature PK (bytes 0x50 0x4B 0x03 0x04) at offset zero.

How to open CUIX files

Important: Different programs may use files with the CUIX file extension for different purposes, so unless you are sure which format your CUIX file is, you may need to try a few different programs.

We have not yet verified any programs for Windows that work with this specific file format. If you know one, please use the 'Suggest a program' link below. Thanks!

Last updated: September 19, 2026

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