Hermes Guide (v1.5.0)


Hermes is an open-source Rust implementation of a relayer for the Inter-Blockchain Communication protocol (IBC) released under the ibc-relayer-cli crate. It provides a CLI to relay packets between Cosmos SDK chains, exposes Prometheus metrics and offers a REST API.

This guide can help you set up, configure, operate and monitor Hermes to relay packets between two or more IBC-enabled chains.

About Hermes

An IBC relayer is an off-chain process responsible for relaying IBC datagrams between any two chains. The way it does so is by scanning chain states, building transactions based on these states, and submitting the transactions to the chains involved in the network.

The relayer is a central element in the IBC network architecture. This is because chain modules in this architecture are not directly sending messages to each other over networking infrastructure, but instead they create and store the data to be retrieved and used by a relayer to build the IBC datagrams.

We sometimes refer to Hermes as "IBC Relayer CLI", to make it clear that this is a relayer CLI (i.e., a binary) and distinguish it from the relayer core library (that is the crate called ibc-relayer).

Hermes is actively developed and maintained by Informal Systems in the ibc-rs repository.

Where to go


Lastly, for general questions, you can reach us at, or on Twitter @informalinc.

Note that Hermes is packaged as part of the ibc-relayer-cli crate.

Disclaimer This project is undergoing heavy development, use at your own risk.