About XZ Files
XZ Compressed
XZ provides very high compression ratio using LZMA2, common in Linux packages.
Family
Archives & Compressed
Extension
.xz
MIME Type
application/x-xz
Can Use As
HOW XZ
CAME TO BE.
XZ is a general-purpose compression format released in 2009 by Lasse Collin, based on the LZMA2 algorithm (an evolution of the LZMA Igor Pavlov designed for 7-Zip). The xz-utils suite became the default "best compression ratio" tool on Linux — typically 30% smaller than gzip and 15% smaller than bzip2 at comparable speed.
Every major Linux distribution adopted .tar.xz for kernel and package distribution. Then came March 2024 and the notorious XZ backdoor incident: someone operating under the name Jia Tan spent three years as a trusted xz-utils maintainer, then inserted a malicious payload that would compromise SSH on affected systems. A Microsoft engineer, Andres Freund, caught it by noticing SSH logins were half a second slower than usual. The backdoor was removed, xz-utils went through a governance reshuffle, and the industry learned a hard lesson about single-maintainer supply-chain risk.
CURIOSITIES &
TRIVIA.
The XZ backdoor (CVE-2024-3094) was caught in March 2024 by a Microsoft engineer who noticed SSH logins were ~500 ms slower than usual — arguably the most important security catch of the decade.
XZ compression typically beats gzip by 30% and bzip2 by 15% on general data.
Every modern Linux distribution ships its kernel source as .tar.xz.
XZ supports parallel compression via xz -T flag — essential for utilizing modern many-core CPUs.
The LZMA2 algorithm is a successor to LZMA, originally designed for 7-Zip by Igor Pavlov.
STRENGTHS &
LIMITATIONS.
Strengths
- Best-in-class compression ratio among mainstream tools.
- Streaming-capable — can pipe through network.
- Multi-threaded compression available.
- Mature on every Linux distribution.
- Supports integrity checking (CRC32, CRC64, SHA-256).
Limitations
- Slow compression at high levels — 3-5× slower than gzip.
- Memory-hungry: xz -9 can need 700+ MB to compress.
- 2024 supply-chain backdoor damaged trust in the project.
- Zstandard outperforms xz at similar ratios with less memory.
Typical Sizes & Weights
Text/source archive
15-25% of original
Linux kernel (.tar.xz)
~125 MB
Firefox source code
~600 MB
Technical Specifications
- MIME type
- application/x-xz
- Extensions
- .xz, .txz
- Algorithm
- LZMA2
- Standard
- The .xz File Format specification 1.1.0
- Integrity checks
- None, CRC32, CRC64, SHA-256
CONVERT FROM
XZ
Common Use Cases
Linux packages, high compression
Related Formats
Popular comparisons
XZ vs TAR
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XZ vs BZ2
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XZ vs LZMA
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XZ vs LZ4
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Popular XZ conversions
The most-requested destinations when starting from XZ.
Frequently Asked Questions about XZ
Frequently Asked Questions
XZ (XZ Compressed) is an archive format used to bundle multiple files and folders into a single compressed file. The archive preserves the directory structure and typically reduces total size via compression. XZ sits in the archives & compressed family and has specific strengths around compression ratio, speed, or platform support.
7-Zip, WinRAR, The Unarchiver (macOS), and the built-in archive utilities on Windows and macOS open most XZ files. For command-line extraction, 7z, unar, or the format-specific tool handles XZ cleanly. If your extractor does not recognise XZ, convert to ZIP first — ZIP opens on every operating system without extra software.
Upload the XZ to KaijuConverter and pick ZIP, 7Z, TAR.GZ, or RAR as the target. Our pipeline extracts the original archive and re-compresses the contents into the target format. File permissions, timestamps, and directory structure are preserved where both formats support them.
Depends on the goal. ZIP is the universal baseline — every OS extracts it out of the box. Formats like 7Z or TAR.GZ compress better but require specific tools. XZ may win on compression ratio, password support, or OS integration for specific workflows; ZIP wins on raw compatibility.