CCIP v2.0.0 Client API Reference

Client defines the canonical CCIP message format and encoding helpers used by applications.

It provides:

• message structs for sending and receiving cross-chain messages
• encoding utilities for chain-specific execution parameters (extraArgs)
• common types used across Router, OnRamp, and OffRamp interactions

All CCIP message construction and decoding relies on this library.

This library provides reusable helper functions and is not deployed as a standalone application-facing contract.

Usage Boundary

You use this library when constructing or decoding CCIP messages.

• Applications use EVM2AnyMessage to send messages through the Router.
• Receiver contracts use Any2EVMMessage to process inbound messages.
• You are responsible for encoding extraArgs correctly for the destination chain.

Contract

libraries/Client.sol

Import

import {Client} from "chainlink-ccip/libraries/Client.sol";

If you have not installed the package:

npm install @chainlink/contracts-ccip@2.0.0

Functions

_argsToBytes

function _argsToBytes(EVMExtraArgsV1 memory extraArgs) internal pure returns (bytes memory bts)

Encodes extra arguments into the format expected by CCIP contracts.

_argsToBytes

function _argsToBytes(GenericExtraArgsV2 memory extraArgs) internal pure returns (bytes memory bts)

Encodes extra arguments into the format expected by CCIP contracts.

_svmArgsToBytes

function _svmArgsToBytes(SVMExtraArgsV1 memory extraArgs) internal pure returns (bytes memory bts)

Encodes SVM-specific execution arguments.

_suiArgsToBytes

function _suiArgsToBytes(SuiExtraArgsV1 memory extraArgs) internal pure returns (bytes memory bts)

Encodes Sui-specific execution arguments.

Constants

EVM_EXTRA_ARGS_V1_TAG

Version tag for EVMExtraArgsV1 encoding.

GENERIC_EXTRA_ARGS_V2_TAG

Version tag for GenericExtraArgsV2 encoding.

SVM_EXTRA_ARGS_V1_TAG

Version tag for SVMExtraArgsV1 encoding.

NO_EXECUTION_ADDRESS

address public constant NO_EXECUTION_ADDRESS = address(bytes20(NO_EXECUTION_TAG));

Special address used to indicate that no receiver execution should occur.

Structs

EVM2AnyMessage

EVMTokenAmount

Any2EVMMessage

EVMExtraArgsV1

GenericExtraArgsV2

SVMExtraArgsV1

SuiExtraArgsV1

Notes

• extraArgs must match the destination chain’s expected format.
• Different chain families (EVM, SVM, Sui) require different extra argument encodings.
• Incorrectly encoded extraArgs may cause message execution to revert.

Usage context

Used by:

• IRouterClient
• CCIPReceiver

Example:

// Construct outbound CCIP message
Client.EVM2AnyMessage memory message = Client.EVM2AnyMessage({
  receiver: abi.encode(receiverAddress),
  data: abi.encode(payload),
  tokenAmounts: tokenAmounts,
  feeToken: address(0),
  extraArgs: Client._argsToBytes(
    Client.GenericExtraArgsV2({
      gasLimit: 300_000,
      allowOutOfOrderExecution: false
    })
  )
});

Related Interfaces & Contracts

• IRouterClient
• CCIPReceiver
• ExtraArgsCodec