> For the complete documentation index, see [llms.txt](https://futaba.gitbook.io/docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://futaba.gitbook.io/docs/protocol/relayer.md).

# Relayer

Relayers act as intermediaries between the source chain and the destination chain. Their main functions are as follows:

* Monitor and receive query requests emitted from the [Gateway Contract](/docs/protocol/gateway.md) on the source chain
* Obtain proof based on the query requests
  * Use `eth_getProof` to obtain account proof and a storage proof
* Send the proof as a transaction to the [Gateway Contract](/docs/protocol/gateway.md) on the source chain

Today, Futaba operates its own Relayer. In the future, we will provide a module to customize Relayer more easily to support Proof of Block Hash when using [Konoha](/docs/protocol/konoha.md), and aim to build a Permissionless Relayer.

The current Fee for Relayer can be found in [Estimate fee](/docs/protocol/light-client/estimate-fee.md).