It's called Landr and basically you can master your songs on it!
Mastering (maybe you already know) but it's basically about making your mixes sound balanced, giving them more presence and also, most importantly, making them louder in volume, so when they get played on the radio, or next to any other 'professional' track, they will stand up next to them in volume and in quality.
Mastering is a MUST for any professional or at least serious musician, who cares about their tracks.
THE DETAILS - You can sign up for many different types of accounts on Landr.
I have signed up for the FREE account. You get 2 Free MP3 masters of your songs a month. Great for demo's / You Tube covers etc.
But also, if you sign up for a new account through my referral link - You (& I ) will both get 2 FREE WAV masters, which are much better quality, ie - you can actually release them on iTunes, Amazon, put them on CD's etc.
If that sounds up your street, sign up via my referral link.
And we will both be winners!
Enjoy your amazing new Free mastering tool !!