.iso MIME type
ISO disk imagearchives
application/x-iso9660-imageDisk images of an ISO 9660 file system — OS installers and optical disc copies.
| MIME type | application/x-iso9660-image |
|---|---|
| Extensions | .iso |
| Content-Type | application/x-iso9660-image |
| Compress in transit? | No — already compressed |
| File signature | 43 44 30 30 31 (CD001) at offset 32769 |
Good to know
- Windows and macOS mount ISO files natively. Linux installer ISOs are usually hybrid images you can write straight to a USB stick.
- ISOs are big: make sure the server supports range requests so interrupted downloads can resume.
Useful here: Accept-Ranges header
Serve .iso files with the right type
The response header to send:
Content-Type: application/x-iso9660-image
Most servers pick the type from the file extension. If yours sends the wrong one, map it explicitly:
nginx (inside the types block in mime.types)
application/x-iso9660-image iso;
Apache (.htaccess or server config)
AddType application/x-iso9660-image .iso
Express
res.set("Content-Type", "application/x-iso9660-image");Python
import mimetypes
mimetypes.add_type("application/x-iso9660-image", ".iso")HTML file input
<input type="file" accept=".iso,application/x-iso9660-image">
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.iso | grep -i '^content-type:' file --mime-type file.iso
Frequently asked questions
What is the MIME type for .iso files?
application/x-iso9660-image.
What Content-Type header should a .iso file be served with?
Content-Type: application/x-iso9660-image. It's already compressed, so servers shouldn't gzip it.
How can I tell if a file is really a .iso?
Check its bytes rather than the extension: ISO files contain 43 44 30 30 31 (CD001) at byte offset 32769. On the command line, file --mime-type name.iso does this for you.
Related types
Headers that go with it: Content-Type · Content-Disposition · X-Content-Type-Options