Are dapps free?

Yes and no. Most dapps require you to pay in order to use them, but the cost of using a dapp is generally much lower than the cost of using a traditional app. For example, the cost of using Augur, a popular dapp, is only 0.5% of the value of the transaction. Compare that to the 4-6% average fee that credit card companies charge for transactions, and it's easy to see why dapps are gaining in popularity.