OptimFROG is a lossless audio compression program. Its main goal is to reduce at maximum the size of audio files, while permitting bit identical restoration for all input.

OptimFROG usually obtains the best lossless audio compression ratios. It has fully featured input plug-ins for the Windows Media Player, foobar2000, Winamp 2/3/5, dBpowerAMP, XMPlay, QCD, and XMMS audio players (with bitstream error resilience, ID3v1.1 and APEv2 read tagging support, ID3v2 compatible), optimal support for all integer PCM wave formats up to 32 bits and an extensible streamable (error tolerant) compressed format. It is also fast, the default mode encodes CD quality audio data at 12.4x real-time and decodes at 17.4x real-time on AMD Athlon XP 1800+ (the fastest mode encodes at 28.1x real-time and decodes at 24.7x real-time). Self-extracting (sfx) archives can also be created with a small overhead of just 54 kB.

The compression ratios which can obtained with OptimFROG are generally ranging from 25% (silent classical music) to 70% (loud rock music) of the original audio file size. This is less compared with around 13% obtained with high quality MP3 files (~176 kbps), but you have the great advantage of archiving and listening at perfect copies of your original music.

OptimFROG uses a new audio compression technology, the generalized stereo decorrelation concept (together with the optimal predictor), which was first introduced with OptimFROG 4.0b in December 2001. At the time of its introduction, the new technology yielded significantly better (~1.5%) compression than existing state-of-the-art lossless audio compressors.