A base swap exchanges tokens through a liquidity pool on Base if your wallet holds the input token there and enough ETH for gas. To make that trade, the base swap app connects your wallet to BaseSwap liquidity pools. You can also supply paired tokens to a pool, earning trading fees while accepting price risk.
A liquidity pool sets the swap quote
A liquidity pool sets your quote according to its available tokens, the size of your trade, and its fee. An automated market maker, or AMM, adjusts the price as a trade changes the pool’s token balances. On the BaseSwap DEX, a smart contract executes the exchange against that liquidity without waiting for another trader to accept your order.
Base is Coinbase’s Ethereum layer 2, so assets on Base and Ethereum mainnet are separate balances even when you use the same wallet address. ETH or USDC held only on mainnet cannot fund a Base trade. You need the token you intend to sell on Base before you can swap it there.
Deeper liquidity generally means less price impact: your own trade moves the pool’s price less. Slippage is different; it is a change between the quote you see and the price at execution. A slippage limit can protect your minimum received if the price moves, but it cannot improve a poor quote from a thin pool.
You need Base assets, gas, and an acceptable quote
To trade, you need a wallet using Base, the input token on Base, and some ETH on Base for gas. If your funds are on another network, transfer them to Base through a bridge or withdraw directly to Base if your source offers that network. Then choose the token to sell, the token to receive, and the amount.
Compare the quoted output with the input’s reference value before confirming. For example, if ETH is worth 2,500 USDC, a sale of 0.1 ETH starts from a 250 USDC reference value. An illustrative quote of 248 USDC could reflect the pool fee and price impact; gas is paid separately in ETH. At an illustrative 0.5% slippage limit, the minimum received on that quote is 246.76 USDC.
Pool fees depend on the pool, while gas depends on Base network demand and the transaction’s complexity. Check the estimated gas and minimum received, especially for a small trade. If the quote is poor, a smaller trade may reduce price impact; raising the slippage limit will not.
Before signing, verify the output token’s contract address so you do not buy a lookalike. Selling an ERC-20 token may also require a separate approval transaction that lets a contract spend that token. Check the spender and allowance in your wallet; approval and the swap can each require gas.
Providing liquidity earns fees and changes what you hold
Providing liquidity means depositing assets that other traders can swap against. You typically supply two tokens at the pool’s current value ratio and receive a position representing your share. Swap fees can accrue to that position, while any separate liquidity farming rewards depend on the pool’s current incentives.
Your token amounts change as trades pass through the pool. If ETH rises against USDC, an ETH/USDC position tends to hold less ETH and more USDC than the amounts you deposited. The resulting gap against simply holding those original amounts is called impermanent loss; trading fees may or may not offset it.
If you want only the output token, check the quote and complete the swap. If you want to provide liquidity, first compare the pool’s trading activity, fees, and token exposure with the return you would need. When you withdraw, expect the pool’s current mix of tokens, which may differ from what you deposited.