GZIP file format

.gz · .gzip · compression (single file) · introduced 1992 by Jean-loup Gailly & Mark Adler

What is a GZIP file?

GZIP is a single-file compressor based on DEFLATE, written by Jean-loup Gailly and Mark Adler in 1992 as a free replacement for the patented Unix compress utility. It compresses one file at a time and is almost always paired with TAR (.tar.gz) when you need to bundle a directory. GZIP is the default Content-Encoding of the web — every browser and HTTP client speaks it natively.

Most readers reach this page after double-clicking a .gz file and finding their operating system unsure what to do with it. The good news: GZIP is a well-understood format with mature tooling on every major platform. It is supported in one click by mainstream archivers on Windows, macOS, and Linux.

How to extract a GZIP file

Opening a .gz file is straightforward on every modern operating system. The exact steps depend on which platform you are on:

On Windows

Locate the .gz file in File Explorer.
Right-click the file. If you have 7-Zip installed, choose 7-Zip → Extract Here. On Windows 11 the built-in extractor handles ZIP, 7z, RAR and several other formats directly through Extract All…
If prompted, pick a destination folder and click Extract.
The extracted files appear in a folder next to the original archive.

On macOS

Find the .gz file in Finder.
Install The Unarchiver from the Mac App Store, or Keka for both creating and extracting.
Right-click the file → Open With → The Unarchiver (or just double-click after Unarchiver is set as the default).
The extracted folder appears next to the archive.

On Linux

Use your file manager: right-click the archive → Extract Here (file-roller on GNOME, Ark on KDE).
On the command line, run one of:
```
gArchive Explorer file.gz
```
The files appear in the current directory.

How to create a GZIP file

To pack files into a .gz archive, you typically need an archiver that supports writing this format. Not every tool can create every format — for example, only WinRAR can create real RAR files. The sidebar lists the software known to read and write GZIP.

On the command line, the canonical create command is:

gzip file

If you regularly create archives at scale, a dedicated archive automation suite can wrap this command in scheduled jobs, integrity checks, and offsite replication.

Strengths

Fast
Streamable
Universal
Standardized (RFC 1952)

Weaknesses and limitations

Single file only
Older algorithm — XZ/Zstd compress smaller
No integrity beyond CRC32

Typical use cases

HTTP transport compression
Log rotation
Source tarballs (.tar.gz / .tgz)
Streaming pipelines

Technical details

GZIP uses the DEFLATE algorithm and is identified on disk by the magic byte sequence 1F 8B. The standard MIME type is application/gzip. The format is an open specification and is free for any use.

Frequently asked questions

Is GZIP safe to open?

Archive files are containers — they are only as safe as what they contain. A .gz from a trusted source is fine; one received from a stranger can hold malicious executables, scripts, or files engineered to exploit bugs in your archiver. Always keep your archiver updated, and never run unknown executables that come out of an archive. A safe workflow is to extract into a sandbox and scan the contents before opening anything.

What is the maximum file size?

Modern implementations support archives in the multi-terabyte range. The practical limit is your filesystem (FAT32 caps at 4 GB; ext4, NTFS, APFS, and exFAT all comfortably handle multi-TB files).

Can I password-protect a GZIP?

Not natively. TAR and the standard Unix compressors do not include encryption. Wrap the archive with GnuPG or age for confidentiality, or use a format like 7z that builds AES-256 in.

How does GZIP compare to other formats?

See our format comparison pages such as ZIP vs 7z, ZIP vs RAR, and tar.gz vs tar.xz for side-by-side feature tables.