Wiktionary
free of charge
a. Not requiring any payment. adv. Without any payment being required.
WordNet
Usage examples of "free of charge".
Next, bis food and drink are of the highest quality and provided free of charge, at his pleasure and to his order.
Since the Flood, most green riders had been giving all their customary courier services free of charge.
That terminal will accept your call free of charge, courtesy of Golden Rule.