Are you ready to rock out at the largest free concert in America?! We bet you are! John Mayer, Demi Lovato, Ne-Yo and J. Cole are all set to perform at the 2013 Philly 4th of July Jam!

The Roots, who are Philadelphia natives, will serve as the house band for this extravaganza that will kick off (duh) July 4 on Benjamin Franklin Parkway as a part of the city's Welcome America! weeklong festival. The mayor of Philly, Michael A. Nutter, praised the concert lineup in a press release (via Billboard) as an, "incredibly talented group of musicians." We couldn't agree more!

John Mayer, of course, is coming off a vocal surgery and his Philly 4th of July Jam will kick off extensive touring for the singer-songwriter in support of his upcoming album that is due out in June. Having been away from the stage for quite some time, Mayer's tour will run from July until October.

Demi Lovato hasn't announced any significant touring plans yet besides her Wango Tango  and KISS 108 concerts, so this could be the start of a large string of shows for the 'Heart Attack' singer as well. At least that's what we're hoping! She does have to promote her upcoming 'DEMI' album afterall...

What better way to celebrate freedom on the 4th of July than in Philly with Demi Lovato and John Mayer?

Watch the Demi Lovato 'Heart Attack' Video