.xz MIME type
XZ filearchives
application/x-xzLZMA2-compressed files — the .tar.xz archives used by the Linux kernel and many distributions.
| MIME type | application/x-xz |
|---|---|
| Extensions | .xz |
| Content-Type | application/x-xz |
| Compress in transit? | No — already compressed |
| File signature | FD 37 7A 58 5A 00 (.7zXZ.) |
Good to know
- Compresses better than gzip and bzip2 at the cost of slow compression; decompression is fast.
- The 2024 xz-utils backdoor (CVE-2024-3094) was a compromise of the library's release tarballs, not a flaw in the format.
Serve .xz files with the right type
The response header to send:
Content-Type: application/x-xz
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-xz xz;
Apache (.htaccess or server config)
AddType application/x-xz .xz
Express
res.set("Content-Type", "application/x-xz");Python
import mimetypes
mimetypes.add_type("application/x-xz", ".xz")HTML file input
<input type="file" accept=".xz,application/x-xz">
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.xz | grep -i '^content-type:' file --mime-type file.xz
Frequently asked questions
What is the MIME type for .xz files?
application/x-xz.
What Content-Type header should a .xz file be served with?
Content-Type: application/x-xz. It's already compressed, so servers shouldn't gzip it.
How can I tell if a file is really a .xz?
Check its bytes rather than the extension: XZ files start with FD 37 7A 58 5A 00 (.7zXZ.). On the command line, file --mime-type name.xz does this for you.
Related types
Headers that go with it: Content-Type · Content-Disposition · X-Content-Type-Options