What Is the Role of a “Relayer” in a DEX Aggregator’s Transaction Process?

In some DEX aggregator architectures, a relayer is an off-chain entity that helps construct, sign, and broadcast a transaction to the blockchain on behalf of the user. This can be used to facilitate gasless swaps or complex order routing.

The relayer essentially acts as a transaction proxy, abstracting away some of the complexity and potentially optimizing the transaction's inclusion in a block, often in exchange for a fee.