.msi MIME type
Windows Installer packageapps & binaries
application/x-msiWindows Installer packages. No type is registered; application/x-msi is the common one.
| MIME type | application/x-msi |
|---|---|
| Extensions | .msi |
| Also seen as | application/x-msdownload |
| Content-Type | application/x-msi |
| Compress in transit? | No — already compressed |
| File signature | D0 CF 11 E0 A1 B1 1A E1 the OLE2 compound-file signature shared by legacy Office formats |
Good to know
- MSI files share the OLE2 signature with legacy Office documents, so the first bytes alone don't identify them.
- Like
.exedownloads, they carry the Mark of the Web and trigger SmartScreen warnings unless signed.
Serve .msi files with the right type
The response header to send:
Content-Type: application/x-msi
Most servers pick the type from the file extension. If yours sends the wrong one, map it explicitly:
application/x-msi msi;
AddType application/x-msi .msi
res.set("Content-Type", "application/x-msi");import mimetypes
mimetypes.add_type("application/x-msi", ".msi")<input type="file" accept=".msi,application/x-msi">
Check it
See what a server sends for a file, and what type a local file really is by its contents:
curl -sI https://example.com/file.msi | grep -i '^content-type:' file --mime-type file.msi
Frequently asked questions
What is the MIME type for .msi files?
application/x-msi. You may also see application/x-msdownload, but application/x-msi is the one to send.
What Content-Type header should a .msi file be served with?
Content-Type: application/x-msi. It's already compressed, so servers shouldn't gzip it.
How can I tell if a file is really a .msi?
Check its bytes rather than the extension: MSI files start with D0 CF 11 E0 A1 B1 1A E1 — the OLE2 compound-file signature shared by legacy Office formats. On the command line, file --mime-type name.msi does this for you.
Headers that go with it: Content-Type · Content-Disposition · X-Content-Type-Options