Windows Installer Package — Microsoft Installer package for Windows software.
Quick facts
What is .msi
A .msi file is a Windows Installer Package — Microsoft Installer package for Windows software.
In the mime-db registry it maps to application/octet-stream, and it is marked as compressible. When serving .msi over HTTP, set the Content-Type header as shown in Developer info below.
Related entities: it maps to application/octet-stream — and is delivered over HTTP via the Content-Type header.
How to open .msi files
Developer info
When served over HTTP, responses should set the following header:
Content-Type: application/octet-stream
Common software that reads/writes .msi:
Relation chain
Related extensions
Related MIME types
Common uses
How to edit .msi files
How to create .msi files
Frequently asked questions
Common options include Windows Installer, 7-Zip. You can also open many of these files with built-in viewers or a browser.
Create a new file in any text editor or the app that owns the format and save it with the .msi extension.
application/octet-stream is the media type identifier used for .msi files during network transfer (for example in the HTTP Content-Type header).
Sources & standards
Updated 2026-08-18
Explore this reference