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Friday, 25 March 2016


Extremely Fast Compression algorithm 
LZ4 is lossless compression algorithm, providing compression speed at 400 MB/s per core, scalable with multi-cores CPU. It also features an extremely fast decoder, with speed in multiple GB/s per core, typically reaching RAM speed limits on multi-core systems.
Speed can be tuned dynamically, selecting an "acceleration" factor which trades compression ratio for more speed up. On the other end, a high compression derivative, LZ4_HC, is also provided, trading CPU time for improved compression ratio. All versions feature the same excellent decompression speed.
masterBuild Status Build status coverity
devBuild Status  Build status
Branch Policy:
  • The "master" branch is considered stable, at all times.
  • The "dev" branch is the one where all contributions must be merged before being promoted to master.
    • If you plan to propose a patch, please commit into the "dev" branch, or its own feature branch. Direct commit to "master" are not permitted.


The benchmark uses the Open-Source Benchmark program by m^2 (v0.14.3) compiled with GCC v4.8.2 on Linux Mint 64-bits v17. The reference system uses a Core i5-4300U @1.9GHz. Benchmark evaluates the compression of reference Silesia Corpus in single-thread mode.
memcpy1.0004200 MB/s4200 MB/s
LZ4 fast 17 (r129)1.607690 MB/s2220 MB/s
LZ4 default (r129)2.101385 MB/s1850 MB/s
LZO 2.062.108350 MB/s510 MB/s
QuickLZ 1.5.1.b62.238320 MB/s380 MB/s
Snappy MB/s960 MB/s
LZF v3.62.073175 MB/s500 MB/s
zlib 1.2.8 -12.73059 MB/s250 MB/s
LZ4 HC (r129)2.72022 MB/s1830 MB/s
zlib 1.2.8 -63.09918 MB/s270 MB/s


The raw LZ4 block compression format is detailed within lz4_Block_format.
To compress an arbitrarily long file or data stream, multiple blocks are required. Organizing these blocks and providing a common header format to handle their content is the purpose of the Frame format, defined into lz4_Frame_format. Interoperable versions of LZ4 must respect this frame format.

Other source versions

Beyond the C reference source, many contributors have created versions of lz4 in multiple languages (Java, C#, Python, Perl, Ruby, etc.). A list of known source ports is maintained on the LZ4 Homepage.