QuickLZ 1.5.x
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QuickLZ is the world's fastest compression library, reaching 308 Mbyte/s per core. It can be used under a commercial license if such has been acquired or under GPL 1, 2 or 3 where anything released into public must be open source.
  • Simple to use and easy to integrate. Get done in minutes and continue developing!
  • Streaming mode for optimal compression ratio of small packets down to 200 - 300 bytes in size.
  • Auto-detection and fast treatment of incompressible data.

Latest stable versions:

  QuickLZ C 1.5.0 08-Jan-2011
QuickLZ DLL 1.5.0 08-Jan-2011
  QuickLZ Java 1.5.0 08-Jan-2011
  QuickLZ C# 1.5.0 08-Jan-2011

Latest beta version:

  QuickLZ C 1.5.1 BETA 7 07-Oct-2011

The C version compiles trouble-free on many platforms such as Visual Studio on Windows, gcc on Linux, LLVM on FreeBSD, Xcode for iPhone, aCC for SPARC, xlC for POWER, and for ARM, SH4/5, etc, etc.

Library Level Compressed size Compression Mbyte/s Decompression Mbyte/s
QuickLZ C 1.5.0 1 47.9% 308 358
QuickLZ C 1.5.0 2 42.3% 131 309
QuickLZ C 1.5.0 3 40.0% 31 516
QuickLZ C# 1.5.0 1 47.9% 133 132
QuickLZ Java 1.5.0 1 47.9% 127 95
LZF 3.1 UF 54.9% 204 396
LZF 3.1 VF 51.9% 193 384
FastLZ 0.1.0 1 53.0% 173 442
FastLZ 0.1.0 2 50.7% 167 406
LZO 1X 2.02 1 48.3% 169 434
zlib 1.22 1 37.6% 55 234
Core i7 920 benchmark. Details

27-Dec-2015 Closed www.exdupe.com and moved it to this domain instead. It can now be found at www.quicklz.com/exdupe
19-Nov-2011 Released qzip - a nice gzip-like command line tool.
29-Mar-2011 Released 1.5.1 BETA 1 with ground breaking performance increase for the C version in level 1 on 64-bit x64 architectures.
08-Jan-2011 Released 1.5.0 final after a year of beta testing, regression testing, code reviewing and static analysis tooling! :)
29-Nov-2010 If you're currently a happy qpress user, please see www.exdupe.com for a beta version of a new deduplication file archiver.
23-Sep-2010 Released qpress 1.1. Replaced yet another stat() call by native GetFileAttributes() in Windows because it could fail opening a source file. That error should now be definitely fixed.
27-Jul-2010 Released qpress 1.0 as final! Note that command line flags for pipes and redirection have changed because of problems when running qpress as cronjob.
28-Jun-2010 We are currently working on fast block based data deduplication - trying to compete with hardware speeds!
22-Apr-2010 Released QuickLZ 1.4.1 final, after more than a year of beta testing by our users, code inspection, and execution of dynamic analysis tools and test programs on various combinations of architectures and operating systems.
20-Apr-2010 Recompiled qpress.exe and qpress64.exe because version 0.39 was accidently compiled with dependencies not present on some Windows XP machines.
04-Jan-2010 Released qpress 0.39. Replaced stat() by native GetFileAttributes() on Windows because we had a report that qpress failed opening a source file during compression. Also removed a few -Wall warnings on Solaris gcc.
02-Jan-2010 Updated benchmarks from the Core 2 Duo and Athlon 6400+ in 32-bit mode to a single Core i7 920 in 64-bit mode.
27-Nov-2009 Released qpress 0.38. Improved benchmark accuracy (with -m flag) and other minor details. No bug fixes. Also upgraded to QuickLZ 1.4.1 BETA 3.
26-Nov-2009 Added support for level 3 in the C# and Java versions of 1.5.0. Of course compressed data is compatible between the C/DLL, Java and C# versions.

qpress file archiver

qpress is a portable file archiver using QuickLZ and designed to utilize fast storage systems to their max. It's often faster than file copy because the destination is smaller than the source. A few features:

  • multiple cores, reaching upto 1.1 Gbyte/s in-memory compression on a quad core i7

  • 64-bit file sizes and tested with terabyte sized archives containing millions of files and directories

  • pipes and redirection and *nix-like behaviour for scripting and flexibility

  • Adler32 checksums to ensure that decompressed data has not been corrupted

  • data recovery of damaged archives with 64 Kbyte grannularity

  • unbuffered disk I/O (Windows only) to prevent disk cache of other applications from being flushed


For other architectures and operating systems, unzip the source and run 'make':

qpress-11-source.zip (23-Sep-2010)

For many use cases it's now superseded by www.quicklz.com/exdupe

qzip / qcat is a compressor by Daniel Eisner which is command line compatible (not data compatible) with gzip / gzcat: qzip.tar

You will only receive an e-mail upon release of a new final version or if an important bug has been found. Your e-mail address is kept confidential. E-mail: