FLAC (/flæk/; Free Lossless Audio Codec) is an audio coding format for lossless compression of digital audio and is also the name of the free software project producing the FLAC tools, the reference software package that includes a codec implementation. Digital audio compressed by FLAC's algorithm can typically be reduced to between 50 and 70 percent of its original size and decompress to an identical copy of the original audio data.
FLAC is an open format with royalty-free licensing and a reference implementation which is free software. FLAC has support for metadata tagging, album cover art, and fast seeking.
Development was started in 2000 by Josh Coalson. The bit-stream format was frozen when FLAC entered the beta stage with the release of version 0.5 of the reference implementation on 15 January 2001. Version 1.0 was released on 20 July 2001.
On 29 January 2003, the Xiph.Org Foundation and the FLAC project announced the incorporation of FLAC under the Xiph.org banner. Xiph.org is behind other free compression formats such as Vorbis, Theora, Speex, and Opus.
Version 1.3.0 was released on 26 May 2013, at which point development was moved to the Xiph.org git repository.