An MSIX file is a Zip-compressed package used to distribute and install an application in Windows 10 version 1809 and later. It contains the application data files and .XML configuration files, which are required for installing the app. The MSIX file format is based on the .MSI, .APPX, ClickOnce, and App-V installation technologies.

MSIX is designed to be a universal package format for developers to distribute their programs to users through the Microsoft Store. It was introduced in 2018 with the release of Windows 10 version 1809. It supports classic Win32 apps and is designed to eventually replace AppX, MSI, and other Windows installer formats. MSIX offers enhanced security, streamlined app updates through Windows, and cleaner app uninstallation. Several programs can create MSIX packages. These include Microsoft Visual Studio, MSIX Packaging Tool, and Caphyon Advanced Installer. If you have an existing app that you want to save in the MSIX format, you can use the MSIX Packaging Tool to repackage your app. To open an MSIX file and begin installation of the packaged app in Windows 10, simply double-click the file. App Installer opens the MSIX file and displays information about the app, such as the name, publisher, and version, as well as the capabilities requested by the app. Then follow the prompts in App Installer to complete the installation. MSIX packages are extracted to the ProgramFiles\WindowApps directory. If you want to examine the contents of an MSIX file instead of installing the packaged app, you can extract the contents using a Zip decompression utility, such as WinZip or WinRAR. To extract the contents, change the .msix file extension to .zip, then extract the files using the file decompression program. Make sure to change the .zip file extension back to .msix before installing the app.