Archive Explorer

← All formats

Zstandard file format

.zst · .zstd  ·  compression (single file)  ·  introduced 2016 by Yann Collet (Facebook)

What is a Zstandard file?

Zstandard, or zstd, is a modern compression algorithm released by Facebook in 2016. It targets a wide range of compression levels (1-22), giving developers the choice between gzip-class speed and xz-class ratios from a single tool. Zstd has become the default compression for Arch Linux packages, Btrfs, ZFS, and the Linux kernel.

Most readers reach this page after double-clicking a .zst file and finding their operating system unsure what to do with it. The good news: Zstandard 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 Zstandard file

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

On Windows

  1. Locate the .zst file in File Explorer.
  2. 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…
  3. If prompted, pick a destination folder and click Extract.
  4. The extracted files appear in a folder next to the original archive.

On macOS

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

On Linux

  1. Use your file manager: right-click the archive → Extract Here (file-roller on GNOME, Ark on KDE).
  2. On the command line, run one of: 
    7z x archive.zst    # works for almost any format
  3. The files appear in the current directory.

How to create a Zstandard file

To pack files into a .zst 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 Zstandard.

On the command line, the canonical create command is:

# Use 7-Zip, PeaZip, or the format's reference tool to create .zst files.

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

  • Wide speed/ratio tradeoff
  • Very fast decompression
  • Dictionary mode for tiny files
  • Open and standardized (RFC 8478)

Weaknesses and limitations

  • Newer — older systems may not have it
  • Less compression than xz at extreme levels

Typical use cases

  • Filesystem compression (Btrfs, ZFS)
  • Real-time streaming compression
  • Arch Linux packages (.pkg.tar.zst)
  • Kafka, RocksDB internal compression

Technical details

Zstandard uses the Zstandard (FSE + LZ77) algorithm and is identified on disk by the magic byte sequence 28 B5 2F FD. The standard MIME type is application/zstd. The format is an open specification and is free for any use.

Frequently asked questions

Is Zstandard safe to open?

Archive files are containers — they are only as safe as what they contain. A .zst 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 Zstandard?

Some archivers can wrap Zstandard files in an encrypted container, but the format itself does not always include built-in encryption. Check your archiver's documentation.

How does Zstandard 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.

Related formats