What is another word for costing nothing?
Pronunciation: [kˈɒstɪŋ nˈʌθɪŋ] (IPA) 
The phrase "costing nothing" often holds a positive connotation, as it implies something is free and easily obtainable. There are a number of synonyms that can be used in place of this phrase. For example, the phrase "free of charge" means the same thing as "costing nothing," while the word "complimentary" implies that something is being given as a courtesy. Another synonym for "costing nothing" is "gratis," which often has a slightly more formal connotation. Other options include "without charge," "at no cost," and "for free." Regardless of which synonym you choose, the message remains the same: something is being given or offered with no expectation of payment.
