File Extension Search

.msi File Extension

Developer: Microsoft Corporation
File type: Windows Installer Package File
You're here because you have a file that has a file extension ending in .msi. Files with the file extension .msi can only be launched by certain applications. It's possible that .msi files are data files rather than documents or media, which means they're not meant to be viewed at all.

what is a .msi file?

MSI files are also called Windows installer package files, which are used to distribute Windows updates and installers of third party programs that were developed for Windows-based systems. Upon activating these MSI files, the installation process for the associated application or Windows update is initialized, in order to perform the necessary operations for installing the application or update into the Windows-based computer. The content of these MSI files are usually component files and resource libraries of an application or Windows update, which are unloaded unto the system during the installation process, following the installation commands and instructions that are also packaged into these MSI files. Microsoft (for Windows Update) and third party developers create and distribute these Windows installer packages as files appended with the .msi extension, which may also be decompressed using the 7-Zip software.

how to open a .msi file?

Launch a .msi file, or any other file on your PC, by double-clicking it. If your file associations are set up correctly, the application that's meant to open your .msi file will open it. It's possible you may need to download or purchase the correct application. It's also possible that you have the correct application on your PC, but .msi files aren't yet associated with it. In this case, when you try to open a .msi file, you can tell Windows which application is the correct one for that file. From then on, opening a  .msi file will open the correct application. Click here to fix .msi file association errors

applications that open a .msi file

Microsoft Windows Installer

Microsoft Windows Installer

A Windows Installer patch (.msp file) is a self-contained package that has the updates to the application and describes which versions of the application can receive the patch. An application that has been established using the Microsoft Windows Installer can be advanced by reinstalling an updated installation package (.msi file), or by applying a Windows Installer patch (an .msp file) to the application. Patches handles at a minimum of two database transforms and can contain patch files that are saved in the cabinet file stream of the patch package. Servicing applications by distributing a Windows Installer patch, relatively than a complete installation package for the updated product can have advantages. A patch can handle an entire file or only the file bits necessary to update part of the file. This can enable the user to download an upgrade patch that is much smaller than the installation package for the entire product. An update using a patch can protect a user customization of the application thru the upgrade.


Equipped with a high compression ratio (as high as 7z format via LMZA and LMZA2), 7-Zip is an open-source ZIP archiver software that is usable on any computer regardless of operating system installed from the latest to the earlier versions and without any charge at all. Majority of the source codes used by this program are on the list of GNU LGPL License. These include unRar, RAR,ZIP, ARJ, XZ, Z, TAR, WIM, BZIP2, GZIP, CAB, HFS, LZMA, NSIS, CPIO, RPM, VHD, DEB, CHM, LZH, MBR, FAT, NTFS, XAR, DMG, CramFS, ISO, MSI, SquashFS, and UDF. Technically, formats ZIP and GZIP have a ratio of 2 to 10%, 7z has high ratio from 30 to 70% plus this same format has self extracting capability while both ZIP and 7z has AES 256 encryption. Other features include windows shell, file manager, command line version, FAR manager plug-in and localizations for languages up to 79.

a word of warning

Be careful not to rename the extension on .msi files, or any other files. This will not change the file type. Only special conversion software can change a file from one file type to another.

what is a file extension?

A file extension is the set of three or four characters at the end of a filename; in this case, .msi. File extensions tell you what type of file it is, and tell Windows what programs can open it. Windows often associates a default program to each file extension, so that when you double-click the file, the program launches automatically. When that program is no longer on your PC, you can sometimes get an error when you try to open the associated file.

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