LZ4 is lossless compression algorithm, providing compression speed > 500 MB/s per core, scalable with multi-cores CPU. It 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 faster speed. 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 decompression speed. . LZ4 is also compatible with dictionary compression, and can ingest any input file as dictionary, including those created by Zstandard Dictionary Builder. (note: only the final 64KB are used). . LZ4 library is provided as open-source software using BSD 2-Clause license.