To be the best free MP3 download app, one should run well on a mobile phone. Besides, it should support music downloads from popular streaming sites. Last but not least, it should offer a fast download speed. If you take all these into account, the OKmusi MP3 download site is your go-to place. It lets you download any music from any website. Besides, you can download all the desired songs in seconds. And no cost is asked for.