Trading is either zero-fee or a small fee depending on the trader's trading activity in the last 30 days. Trading fees have a distinction of a "maker" fee or a "taker" fee.
Maker fees are paid when you add liquidity to our order book by placing a limit order under the ticker price for buy and above the ticker price for sell.
Taker fees are paid when you remove liquidity from our order book, by placing any order that is executed against an order of the order book.
A note about hidden orders: If you place a hidden order, you will always pay the taker fee. If you place a limit order that hits a hidden order, you will always pay the maker fee.
Deposits and withdrawals are free except for international wires.
See the complete and current fee information at bitfinex.com/fees.