MultiLanguage Windows resource data
File type: Settings, options, themes or skins file, System file
Files with mui extension are mainly related to Microsoft Windows are used for language packages with which you can add the default localization of your OS.
Found 4 different file type records with the same mui filename suffix.
File type category:
Settings, options, themes or skins file
System file
Date updated: June 27, 2025
File extension mui is used for multi-language resource files used in Microsoft Windows operating system.
Various .mui files contain individual language resources used by multi-language editions of Windows 2000/XP and they are still used in other versions of Microsoft Windows.
The main purpose of MUI files is to support multiple languages. Instead of creating a separate version of the operating system for each language, Microsoft creates one version and then uses MUI files to translate the user interface into different languages. For example, if you change the language of your Windows operating system, it will load a different MUI file to display the user interface in the selected language. These files are usually located in a folder named "MUI" within the Windows directory on your computer. They should not be manually altered or deleted, as this could cause problems with the operation of the Windows operating system.
These *.mui files can be installed to Windows with the language options in Control Panels.
There is no way how to convert *.mui files to other formats.
Software apps that manage or store settings in mui files:
File type category:
System file
Date updated: May 15, 2018
The mui file extension is also related to MUI-Magic, a program for Amiga platform. MUI is an object oriented system to create and maintain graphical user interfaces.
The mui file contains class/library used for the program.
Probably not meant to be accessed by the user.
Probably cannot be converted to anything else.
Software applications that handle other tasks involving mui files:
Other operating systems or devices
File type category:
Audio and sound file
Date updated: October 5, 2026
Harmony Assistant is music notation and composition software developed by Myriad Software for Windows, macOS and Linux.
The mui file stores instrument data used by Harmony Assistant for its music playback and instrument management features.
This is a program-specific instrument format intended to be used within Harmony Assistant. It is not a standard audio interchange format, and its usefulness outside Harmony Assistant is limited.
Install Harmony Assistant on Windows, macOS or Linux, then load the mui file through the program's instrument features. The file may not open as a song or play as a standalone audio file.
Use Harmony Assistant to export mui files to other formats.
You can also use the instrument data in Harmony Assistant when rendering music to an audio format supported by the program.
Software applications that can open mui files:
Multiplatform
Software apps that create mui files:
Multiplatform
File type category:
Various data file
Date updated: August 7, 2018
The mui file extension is associated with GLUT, a tool that makes it considerably easier to learn about and explore OpenGL programming, developed by OpenGL.org.
MUI format is probably used for one of the resource files used by the program.
Probably not meant to be accessed by the user.
Probably cannot be converted to anything else.
Software applications that handle other tasks involving mui files:
Microsoft Windows
Language
