Google Publishes Data Compression Library

March 2, 2013

Google has announced the availability of Zopfli, a new open-source data compression library.  Zopfli uses an implementation of the deflate compression technique that achieves a higher degree of compression (smaller output size) than previous approaches.  Typically, the output size is 3-8% smaller than that obtained from the zlib library at maximum compression.  The smaller size is achieved at the cost of significantly longer execution time for compression; the time needed to uncompress the data, which can be done with any existing decompression tools for deflate,  is not affected

 The higher data density is achieved by using more exhaustive compression techniques, which make the compression a lot slower, but do not affect the decompression speed.

This means that Zopfli will be best suited to data that will be compressed once, but uncompressed and used many times: for example, the content of a static Web page.

The library is written in C for portability; it implements only the compression processing, since existing tools can be used for uncompression.

Zopfli is bit-stream compatible with compression used in gzip, Zip, PNG, HTTP requests, and others.

The Zopfli library is being released under an Apache 2.0 open-source license.  Google has also released a brief paper [PDF] with results of tests of Zopfli and other deflate compression tools.

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