It's an aggregator of DEX aggregators, we query the price in 1inch, cowswap, matcha... and then offer you the best price among all of them

DefiLlama takes 0 fee on swaps.

You'll get the exact same price swapping through DefiLlama as what you'd get swapping through the chosen aggregator directly.

We do add our referral code to swaps tho, so, for aggregators with revenue sharing, they will send us part of the fee they earn. This is not an extra fee, you'd be charged the same fee anyway, but now a small part of it is shared with DefiLlama. We also integrate aggregators with no fee sharing the best price, and in those cases we don't make any money.

Our aggregator uses the router contract of each aggregator, we don't use any contracts developed by us. Thus you inherit the same security you'd get by swapping directly from their UI instead of ours.

We inflate gas limit of txs on MetaMask by +40% to ensure that there's nothing unexpected that could trigger out-of-gas reverts. This stacks on top of any increase your RPC might apply on gas estimations, along with possible different gas prices between your metamask and our estimation.

All this together means that gas number you see on metamask will always be inflated, while in our UI we display the actual gas that the tx will consume. The extra gas that is not used is just refunded to the user when tx executes.

We execute swaps directly against the router of each aggregator, so there's no difference between a swap executed directly from their UI and a swap executed from DefiLlama.

Thus, if any of the aggregators we integrate does an airdrop in the future, all swaps made through them would be eligible for their airdrop.

Some ETH orders on CowSwap might not get filled because price moves against you too quickly, in those cases the ETH just sits in a contract until it is refunded 30 minutes after your tx.