Musixmatch
Musixmatch is the world’s largest lyrics catalogue (5.5 million song lyrics) that gives you the lyrics to the songs in your music library.
The Floating Lyrics feature displays synced lyrics floating above the application while you play your favourite songs with any music app, YouTube or on your desktop or TV with Chromecast or Android Wear.
Can’t remember the song title? Simply type part of the lyrics to find the song. Another great feature is MusicID which identifies music from radio, TV or any other audio source.
Besides features like Sleep timer and Equalizer, it can automatically fetch song info and cover art for your tracks.
Free for iOS, Android, Windows Phone and web.