EtherDelta - how fees work

How gas (transaction) fees work

Every Ethereum transaction involves a gas fee which is paid to miners on the Ethereum network. On EtherDelta, Ethereum transactions are required for depositing, withdrawing, and trading.

If you're using EtherDelta with MetaMask, you can lower the gas price when you accept a transaction to pay a lower gas fee. We recommend a gas fee of 4 gwei if you don't mind waiting a few blocks for your transaction to confirm. If you're using EtherDelta without MetaMask, the gas price is fixed at 4 gwei.

If you're not using MetaMask, you can set the gas price from the "Gas price" item in the account dropdown (upper right).

Without getting into too much technical detail, a 4 gwei gas price corresponds to the following overall transaction fees:
Transaction Fee
Deposit ETH ~0.0003 ETH
Withdraw ETH ~0.0001 ETH
Deposit token ~0.0001 ETH
Withdraw token ~0.0002 ETH
Trade ~0.0003 ETH
Cancel order ~0.0002 ETH

How platform fees work

Almost everything you do on EtherDelta is free, with only one exception. Here is the full list of exchange fees EtherDelta charges:
Action Fee
Deposit free
Withdraw free
Place an order (add liquidity fee) free
Execute against someone else's order (take liquidity fee) 0.3%

An important feature of EtherDelta is that placing an order doesn't involve an Ethereum transaction. Placing an order involves signing a message, which doesn't cost a gas fee. This means that placing an order on EtherDelta is completely free: there's no Ethereum transaction fee and there's no fee if the order trades. The one and only platform fee EtherDelta charges is a 0.3% fee paid by the person executing an order (paid in the instrument being sold).

source
https://www.reddit.com/r/EtherDelta/comments/6hrvwl/how_fees_work/