Relayer

A relayer is an intermediary service in blockchain ecosystems that forwards or relays transactions or messages between parties or networks. In meta-transaction systems, a user signs a transaction payload instead of submitting it to the network. A relayer submits the transaction to the blockchain on the user's behalf and often pays the associated gas costs. The user may later reimburse the relayer or use a sponsor model.

In cross-chain messaging, relayers are nodes that observe events on a source chain and relay proofs or messages to a destination chain so that a corresponding action can be taken there. They enable interoperability in protocols that rely on relayer networks to deliver payloads with cryptographic proofs.

Relayer networks may be provided as a service by specialized projects and can be integrated into application architectures to enable gasless onboarding, automated execution, or cross-chain calls. The relayer model reduces user friction but introduces centralization and trust considerations, as the relayer sees the user's intended action and can potentially censor or alter messages. Systems mitigate risks by using multiple relayers, cryptographic proofs, and incentives, plus nonce tracking to prevent replay.

Security and economics: relayers must be trusted to forward accurate data; misbehavior can be punished by collateral or protocol rules; users may prefer running their own relayers when possible for privacy. Across networks, relayers play a facilitating role in enabling convenient user experiences and cross-network interactions, while introducing considerations related to trust, incentives, and security.