Uniswap founder Hayden Adams launched UniswapX on EthCC on July 17, 2023. UniswapX provides the best quotes for on-chain trading by aggregating liquidity from various decentralized exchanges.

According to its white paper, UniswapX has five major features:

• UniswapX outsources the execution of transactions to third-party fillers. These fillers can leverage both on-chain and off-chain liquidity to execute trades, ensuring users always get the best price on their orders.
• UniswapX transactions use Permit2 executable off-chain signatures, allowing users to pay gas fees indirectly as part of their transactions, so users do not need to hold the native token of the chain where the transaction is hosted to pay for gas.
• Users do not need to pay gas for failed transactions, and batch settlement and/or order execution directly from the filler's liquidity pool will also be cheaper than trading directly on the Uniswap protocol.
• Unlike AMM, UniswapX can also effectively avoid MEV. It does so by returning any MEV profits generated from orders back to users in the form of better prices. In addition, UniswapX orders are relatively less susceptible to front-running.
• UniswapX can later be expanded to support cross-chain transactions, allowing users to seamlessly trade assets on the original chain for required assets on the target chain.

Essentially, UniswapX allows users to place off-chain limit orders, with selected fillers fulfilling these orders and recording them on-chain while paying gas fees on behalf of the user.

The concept of UniswapX is not new. 1inch has a similar aggregator mechanism, and Cowswap’s solver model functions the same as UniswapX’s filler. Simply put, UniswapX combines the innovations of 1inch and Cowswap with some minor improvements such as gasless transactions and MEV protection. However, given Uniswap’s status as the leading decentralized exchange, UniswapX will likely be much more popular than 1inch and Cowswap.