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What is a .z file?

A .z file is a GZIP Format. This is an archive — a container holding other files, usually compressed. Confusingly, this extension has been used by 2 different formats over the years — they're all listed below.

This extension has been used by more than one format

2 different formats have claimed .z over the years, so two files with the same extension aren't necessarily the same kind of thing.

How to open a .z file

  • 7-Zip (Windows) or Keka / The Unarchiver (Mac) extract most archive formats, including old ones.
  • On Linux, try `7z x`, `unar` or Ark.

The registry records this extension against GZIP Format, Z Compressed Data, so software from that family is the most likely match.

How to convert a .z file

  • Extract the contents, then re-compress as .zip if you need to share them widely.

MIME type

When a .z file travels over the web, servers label it with this MIME type:

application/gzip

What's a MIME type?

The technical record

For archivists, developers and the merely curious: these are the PRONOM registry entries for .z.

Format nameVersionMIME typePUID
GZIP Formatapplication/gzipx-fmt/266
Z Compressed Datafmt/1671

Got another one?