High Quality Content by WIKIPEDIA articles! Rapid Evolution (also known as RE) is a freeware software tool for DJs, providing advanced filtering and searching features suitable for musicians. It can analyze audio files and automatically determine many properties, such as the musical key, beats per minute (BPM), beat intensity and ReplayGain. It currently supports the following file types: MP3, MP4, WAV, FLAC, OGG, AAC and APE. It helps DJs to organize and profile their music, and ultimately assists in the process of mixing music by utilizing song metadata to be able to show harmonically compatible songs and songs of a similar style. It allows DJs to save and remember which songs are good matches (like a personal, digital mixing journal) and to even plan entire mix sets.