How to download music free compatible with itunes?

I haven't downloaded music since Frostwire basically. I was just looking for something along the lines of that so I can put music on my iPhone.

I use some software called Best Video Downloader to download music from YouTube. It's absolutely free and it can download various qualities of videos and audio files. You can also choose which browsers you can download it on. (IE, Chrome or Firefox)

P.S. If you decide to install it, be sure to decline all other miscellaneous software that comes with it unless you want it. Its completely safe, it just extra stuff you probably don't need.

I use, http://www.zippyshare.eu because you can preview the music before you download it and you don't need any software to download it just your web browser. You can just transfer them over to itunes when they are done downloading by viewing them in whatever folder you downloaded them to and dragging and dropping them into itunes.