All transactions on the blockchain require a network fee to be processed, but with UniswapX swaps, the filler pays the network fee on swappers’ behalf.
Fillers price the network fee into the swap price, but can lower transaction costs by batching multiple orders or filling orders from their own private holdings.
Swappers still need to pay network fees under specific circumstances:
- Initial on-chain token approval of Permit2 incurs a network fee.
- Native network tokens (ETH, MATIC, etc.) must be wrapped before they can be swapped on UniswapX which incurs a network fee.