Relayer
Last updated 17 October 2026Last verified 17 October 2026
What is a relayer in DeFi?
An off-chain service that collects signed transactions or messages from users and submits them to a blockchain on their behalf. In DEX protocols, relayers host order books and match trades off-chain before settling on-chain. In cross-chain bridges, relayers listen for events on one network and deliver the corresponding proof to another. A compromised relayer can stall or manipulate cross-chain transfers. See: Cross-Chain Bridges: The CDOs of DeFi.
TradFi equivalentA messaging intermediary carrying an instruction between two systems, the role SWIFT plays between correspondent banks. A compromised relayer can stall or alter the instruction in transit.