Hermes Guide (v1.8.0)


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 informalsystems/hermes repository.

Note that Hermes is packaged as part of the ibc-relayer-cli crate and not the hermes crate, which is unrelated.

Where to go


  • Request a new feature via the feature request issue template;
  • Consult the list of reported issues and search by relevant keywords to see if you're dealing with a known problem;
  • We would be grateful if you can submit a bug report discussing any problem you find, and from there on we can look at the problem together;
  • Reach Hermes developers and other relayer operators in the #hermes channel on the IBC Gang Discord.

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

Disclaimer As with all software offered by Informal Systems, Hermes is offered on an “as is” basis and you use at your own risk. Informal makes no warranties of any kind, express or implied, relating to Hermes, including no warranties of a “bug-free” nature.