GZ file format: what it is and how to use it

gzip is the Unix compression workhorse: DEFLATE in a tiny wrapper that powers .tar.gz, HTTP encoding and thirty years of pipelines. Learn when to use it and what to choose instead.

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What is a GZ file?

A .gz file is a stream compressed with gzip, Jean-Loup Gailly and Mark Adler's free 1992 answer to the patented compress: DEFLATE (LZ77 + Huffman) in a small header with a CRC32 footer. It compresses exactly one stream, which is why .tar.gz (aka .tgz) pairs it with tar for file sets, and why it became the web's Content-Encoding for two decades.

When should you use .gz?

  • Unix convention: .tar.gz is how source code, logs and datasets still ship.
  • Pipelines: zcat/zless/grep chains that never decompress to disk.
  • Universal readability: every OS, language and tool on the planet speaks it.

When is another format a better fit?

For noticeably better ratio and speed today, zstd wins on both axes. For a Windows audience, ZIP is friendlier; for the web's text, Brotli. gzip's value is ubiquity: it is the compression nothing fails to read.

The short version: GZ is the safe middle of compression: not the best at anything, but readable by everything.

How to open a GZ file

On Windows

Double-click the file, or open it with 7-Zip.

In your browser

Open GZ files right in a browser tab or with the dexrr viewer. No install, no upload.

Also opens in

  • 7-Zip
  • WinRAR
  • gzip (Unix)
  • tar (Unix)

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GZ technical details

Full name
GZIP compressed file
Extensions
.gz .gzip
MIME type
application/gzip, application/x-gzip
Magic bytes
1F 8B
Compression
Lossless
Developer
Jean-loup Gailly & Mark Adler (RFC 1952)
Specification
datatracker.ietf.org

GZ questions, answered

How do I open a .gz file?

gunzip, tar -xzf, 7-Zip and most archive tools decompress it. dexrr extracts .gz files directly in your browser.

Can I convert GZ files online?

Yes, dexrr decompresses .gz and repacks the contents locally in your browser to zip or other formats.

Is GZ better than ZIP?

They solve different problems: .gz compresses one stream, .zip archives many files. For Unix pipes gzip is idiomatic; for users ZIP is friendlier.

What is a .tar.gz (or .tgz) file?

A tar archive (the file bundle) compressed with gzip: tar handles many-files-to-one, gzip handles one-to-smaller. Extract with tar -xzf.

Is the GZ format outdated?

Superseded technically by zstd, but its ubiquity is untouchable. It remains the compression baseline everything implements.