What is the CUIX file format?
The .cuix file stores AutoCAD's entire user interface customization in a single portable package. Autodesk introduced .cuix with AutoCAD 2010 as a replacement for the older binary .cui format; the new format uses a ZIP archive container holding XML definition files, making it inspectable with standard archive tools.
Inside the ZIP, XML documents define every customizable UI element: ribbon tabs, panels, and controls; toolbars and flyouts; pull-down and right-click context menus; keyboard shortcuts; double-click actions; mouse button assignments; DIESEL and LISP macro strings; and full custom command definitions with embedded icon images.
AutoCAD loads one main .cuix (default: acad.cuix) alongside any number of partial .cuix files that add UI elements without overriding the base configuration. Autodesk vertical products - Civil 3D, Architecture, MEP - each ship their own .cuix overlays that extend the base ribbon with discipline-specific panels.
The built-in Customize User Interface editor (the CUIED command) is the officially supported way to modify .cuix files. Direct XML editing after renaming to .zip and unzipping is possible but unsupported. Older binary .cui files from AutoCAD 2009 and earlier are automatically converted to .cuix when loaded in any 2010 or later release.
Security & safety
RISK: LOWCUIx files can contain AutoLISP macro code embedded in command definitions, which executes when the associated button or shortcut is triggered in AutoCAD. Only load .cuix files from trusted sources - malicious macros could execute arbitrary commands within AutoCAD's environment (file operations, LISP execution). Do not load unknown .cuix files from untrusted online sources.
Format details
in a nutshellPrograms that open CUIX files
Windows3 apps
AutoCAD (CUI Editor)
Paid Type CUIED in the AutoCAD command line to open the Customize User Interface Editor; load .cuix via File → Load Partial CUI or via the main CUI dialog.
7-Zip (to inspect XML contents)
Open-source Right-click .cuix → Open archive. Extracts the XML and icon files for inspection (not for editing production files).
VS Code or Notepad++ (to edit extracted XML)
Open-source Extract with 7-Zip, open the main XML in VS Code for inspection or manual editing, then re-zip. Not officially supported by Autodesk. 
macOS1 app
AutoCAD for Mac
Paid AutoCAD for Mac uses a similar CUIx-based customization system; access via Customize menu. Technical details
deep spec| Container | ZIP archive; magic bytes `50 4B 03 04` ("PK") identical to any ZIP file |
| Internal content | XML text files defining ribbons, toolbars, menus, keyboard shortcuts, macros, and custom commands |
| Compression | DEFLATE (per-entry ZIP compression) |
| Integrity | ZIP CRC-32 checksum per internal entry |
| Icon assets | BMP and PNG icon image files may be embedded inside the ZIP alongside the XML definitions |
| Main file | `acad.cuix` is AutoCAD's default primary customization file, loaded at every session start |
| Partial files | Additional `.cuix` files that augment the main UI without replacing it; multiple partials can be loaded simultaneously |
| Macro languages | DIESEL expression strings and AutoLISP macro calls supported within command definitions |
| Platform | Windows (primary); AutoCAD for Mac uses a compatible format |
| Predecessor format | Replaces binary `.cui` (AutoCAD 2009 and earlier); older files are auto-converted on load |
| Editing tool | `CUIED` command opens the built-in Customize User Interface editor within AutoCAD |
| Vertical overlays | Civil 3D, Architecture, MEP, and other Autodesk verticals ship their own `.cuix` discipline overlays |
| Released | AutoCAD 2010 (replaced the binary .CUI format) |
| Latest version | current AutoCAD release (AutoCAD 2025 / 2026); format stable since AutoCAD 2010 |
| Specification | help.autodesk.com |
CUIX conversions
Community Q&A
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