Zstd, short for Zstandard, is a fast lossless compression algorithm, targeting real-time compression scenarios at zlib-level compression ratio.

It is provided as a BSD-license package, hosted on Github.

Branch	Status
master
dev

For a taste of its performance, here are a few benchmark numbers from a number of compression codecs suitable for real-time. The test was completed on a Core i7-5600U @ 2.6 GHz, using m^2's fsbench 0.14.3 compiled with gcc 4.8.4, on the Silesia compression corpus.

Name	Ratio	C.speed	D.speed
		MB/s	MB/s
zstd 0.4	2.872	280	670
zlib 1.2.8 -1	2.730	70	300
QuickLZ 1.5.1b6	2.237	370	415
LZO 2.06	2.106	400	580
LZ4 r131	2.101	450	2100
Snappy 1.1.0	2.091	330	1100
LZF 3.6	2.077	200	560

Zstd can also offer stronger compression ratio at the cost of compression speed. Speed / Ratio trade-off is configurable by small increment, to fit different situations. Note however that decompression speed is preserved and remain roughly the same at all settings, a property shared by most LZ compression algorithms, such as zlib. The following test is run on a Core i7-3930K CPU @ 4.5GHz, using lzbench, an open-source in-memory benchmark by inikep compiled with gcc 5.2.1, on the Silesia compression corpus.

Compression Speed vs Ratio	Decompression Speed

Zstd entropy stage is provided by Huff0 and FSE, from Finite State Entropy library.

Its memory requirement can be configured to fit into low-memory hardware configurations, or servers handling multiple connections/contexts in parallel.

Zstd has not yet reached "stable format" status. It doesn't guarantee yet that its current compressed format will remain stable and supported in future versions. During this period, it can still change to adapt new optimizations still being investigated. "Stable Format" is projected sometimes early 2016.

That being said, the library is now fairly robust, able to withstand hazards situations, including invalid inputs. The library reliability has been tested using Fuzz Testing, with both internal tools and external ones. Therefore, it seems now safe to test Zstandard even within production environments.

Branch Policy

The "dev" branch is the one where all contributions will be merged before reaching "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.