.MSI File Extension

Microsoft Installer File

An MSI file is a Windows installation package that contains all necessary data for installing software on a computer. It includes the program files to be installed, exact installation paths, and specific installation instructions. These files are commonly used for Windows updates and third-party software installations.

The MSI format was introduced as part of the Windows Installer service, which replaced the earlier Setup API. The Windows Installer became a standard component of Microsoft Windows, serving as an Application Programming Interface (API) for software installation, removal, and maintenance. The MSI format added significant improvements over previous installation methods, including a GUI framework and automatic generation of uninstallation sequences.

Users typically interact with MSI files by double-clicking them in Windows, which launches the Windows Installer to begin the installation process. The installer follows the instructions in the MSI package to place files in their correct locations, create necessary registry entries, and complete the setup.

Applications and developers use MSI files to package their software in a standardized format that works with Windows' built-in installation system. The MSI format offers a structured approach to installation through its logical organization:

• Products: Represents a complete installed program identified by a GUID
• Features: Groupings that may contain multiple components and sub-features
• Components: Individual units containing program files, folders, registry keys, shortcuts, or COM components
• Key Paths: Critical files, ODBC data sources, or registry keys specified for components

How to Open .MSI as Microsoft Installer File

There are two main ways to work with MSI files:

• Installation: Simply double-click an MSI file in Windows to launch the installation process. This runs the Windows Installer, which guides you through installing the software package.
• Viewing Contents: Since MSI files are compressed archives, you can examine their contents without installing by using archive tools. Programs like 7-Zip, WinRAR, or WinZip can open MSI files to reveal their internal structure and files.

Comparison to EXE Files

While MSI files are similar to EXE files in that both can be used to install Windows programs, they have a key difference. MSI files always contain installers and work through the Windows Installer service. EXE files, however, may contain standalone programs that run directly when double-clicked, without necessarily installing anything.

Security Note

Though MSI files are typically legitimate, they can potentially contain malware. For safety, only open MSI files from trusted sources and avoid double-clicking MSI files received through email or downloaded from unfamiliar websites.

Applications That Open MSI Files

Windows Apps for MSI Files:

• Microsoft Windows Installer Included with OS
• 7-Zip Free

macOS Apps for MSI Files:

• 7-Zip Free

Linux Apps for MSI Files:

• 7-Zip Free