Interchain Standards (ICS) for the Cosmos network & interchain ecosystem.

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Last updateLast update2022-01-08



This repository is the canonical location for development and documentation of the inter-blockchain communication protocol (IBC).

It shall be used to consolidate design rationale, protocol semantics, and encoding descriptions for IBC, including both the core transport, authentication, & ordering layer (IBC/TAO) and the application layers describing packet encoding & processing semantics (IBC/APP).

Contributions are welcome.


Please see ICS 1 for a description of what a standard entails.

To propose a new standard, open an issue.

To start a new standardisation document, copy the template and open a PR.

See PROCESS.md for a description of the standardisation process.

See STANDARDS_COMMITTEE.md for the membership of the core standardisation committee.

See CONTRIBUTING.md for contribution guidelines.

Interchain Standards

All standards at or past the "Draft" stage are listed here in order of their ICS numbers, sorted by category.


Interchain Standard Number Standard Title Stage
1 ICS Specification Standard N/A


Interchain Standard Number Standard Title Stage
2 Client Semantics Candidate
3 Connection Semantics Candidate
4 Channel & Packet Semantics Candidate
5 Port Allocation Candidate
23 Vector Commitments Candidate
24 Host Requirements Candidate
25 Handler Interface Candidate
26 Routing Module Candidate


Interchain Standard Number Standard Title Stage
6 Solo Machine Client Candidate
7 Tendermint Client Candidate
9 Loopback Client Candidate
10 GRANDPA Client Draft


Interchain Standard Number Standard Title Stage
18 Relayer Algorithms Candidate


Interchain Standard Number Standard Title Stage
20 Fungible Token Transfer Candidate
27 Interchain Accounts Draft
29 General Relayer Incentivisation Mechanism Candidate
30 IBC Application Middleware Candidate