> ## Documentation Index
> Fetch the complete documentation index at: https://docs.theblockchainlibrary.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Relayer

> An off-chain actor or service that observes one blockchain and submits messages or proofs to another system.

# Relayer

An off-chain actor or service that observes one blockchain and submits messages or proofs to another system.

## Definition

An off-chain actor or service that observes one blockchain and submits messages or proofs to another system.

## Why it matters

Interoperability allows assets, messages, and applications to operate across otherwise separate networks.

## How it works

Relayers continuously listen to events on a source blockchain via its API or RPC nodes. Once an event is detected, they package the transaction proof and broadcast it to the destination blockchain, where a smart contract verifies the proof against the source chain's known state.

## Real-world example

In the Cosmos ecosystem, anyone can run a relayer process to help pass packets between networks like Cosmos Hub and Osmosis.

## Advantages

* Facilitates permissionless message transport
* Decentralized operation models
* Essential for protocol connectivity

## Limitations

* Relayers may require economic incentives
* Risk of censorship if not diverse
* Maintenance intensive for operators

## Common misconceptions

* Relayers are the ones moving the funds. Relayers only move proof of funds; the smart contracts on both chains handle the actual asset management.
* Relayers can forge transaction data. Relayers cannot change data because the target chain always verifies the cryptographic proof against the source chain's state.

## Related knowledge

* [Bridge](/generated/v2/glossary/bridge) — term
* [Cross-Chain](/categories/cross-chain) — term
* [Wrapped Asset](/generated/v2/glossary/wrapped-asset) — term

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**Canonical knowledge ID:** `glossary:relayer`