MSI file extension

Windows Installer Package

Run a free instant scan for .MSI file errors

The .MSI file format is used by modern versions of Microsoft's Windows Operating system for installing applications. These .MSI files contain information on the files to be installed and their destination, and often contain the actual install files themselves.

These installers are used by many 3rd party applications, as well as official plug-ins and Windows updates.

Many modern archive tools are capable of extracting the contents of .MSI formatted files.

More recent versions of Windows have seen Microsoft prefer the use of .MSU files for Windows Updates.