FLAC (play /ˈflæk/; Free Lossless Audio Codec

FLAC (play /ˈflæk/; Free Lossless Audio Codec) is a codec (compressor-decompressor or coder-decoder) which allows digital audio to be losslessly compressed such that file size is reduced without any information being lost. Digital audio compressed by FLAC’s algorithm can typically be reduced to 50–60% of its original size, and decompressed into 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.

Though FLAC cannot store floating-point data, and playback support in portable audio devices and dedicated audio systems is limited compared to lossy formats like MP3 or uncompressed PCM, FLAC is supported by more hardware devices than competing lossless compressed formats like WavPack.