Krystal is a decentralized application thus you will need to pay the gas fee to interact with Krystal Smart Contract. The gas fee will depend on the function and the status of the blockchain when you make the transaction.
Please check the gas fee carefully before making any transactions.
When using the swap feature, users will pay 8 basic points (bps) on trades. The fee will be collected in the source or destination token of your trade.
Other features such as Transfer and Earn are free. However, some of the supported protocols Krystal interacts with might have their own fee.