EVM Contract Interfaces

This page documents the public methods and events exposed by CCTP smart contracts on EVM-compatible blockchains.

Contract responsibilities

TokenMessengerV2: Entrypoint for crosschain USDC transfer. Routes messages to burn USDC on a source blockchain and mint USDC on a destination blockchain.
MessageTransmitterV2: Generic message passing. Sends all messages on the source blockchain and receives all messages on the destination blockchain.
TokenMinterV2: Responsible for minting and burning USDC. Contains blockchain-specific settings used by burners and minters.
MessageV2: Provides helper functions for crosschain transfers, such as bytes32ToAddress and addressToBytes32, which are commonly used when bridging between EVM and non-EVM blockchains.

Gas optimization tip: If you’re writing your own integration, it’s more gas-efficient to include address conversion logic directly in your contract rather than calling an external contract.

Full contract source code is available on GitHub.

TokenMessengerV2

depositForBurn

Deposits and burns tokens from sender to be minted on destination domain. Minted tokens will be transferred to mintRecipient.

Note: There is a $10 million limit on the amount of USDC that can be burned in a single CCTP transaction. If the amount exceeds this limit, the transaction will revert. If you need to transfer more than this limit, break up your transfers into multiple transactions.For Fast Transfers, you should always check the remaining allowance before initiating a transfer to ensure there is enough to complete your transfer.

Parameters

Field	Type	Description
`amount`	`uint256`	Amount of tokens to deposit and burn
`destinationDomain`	`uint32`	Destination domain ID to send the message to
`mintRecipient`	`bytes32`	Address of mint recipient on destination domain (must be converted to 32 byte array, that is, prefix with zeros if needed)
`burnToken`	`address`	Address of contract to burn deposited tokens on local domain
`destinationCaller`	`bytes32`	Address as `bytes32` which can call `receiveMessage` on destination domain. If set to `bytes32(0)`, any address can call `receiveMessage`
`maxFee`	`uint256`	Maximum fee paid for transfer, specified in units of `burnToken`
`minFinalityThreshold`	`uint32`	Minimum finality threshold at which burn will be attested

Example

Solidity

// Burn 100 USDC on Ethereum for minting on Avalanche
uint256 amount = 100 * 10**6; // 100 USDC
uint32 destinationDomain = 1; // Avalanche
bytes32 mintRecipient = bytes32(uint256(uint160(recipientAddress)));
address burnToken = 0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48; // USDC on Ethereum
bytes32 destinationCaller = bytes32(0); // Anyone can call receiveMessage
uint256 maxFee = 1000; // 0.001 USDC max fee
uint32 minFinalityThreshold = 1000; // Fast Transfer

tokenMessenger.depositForBurn(
  amount,
  destinationDomain,
  mintRecipient,
  burnToken,
  destinationCaller,
  maxFee,
  minFinalityThreshold
);

depositForBurnWithHook

Deposits and burns tokens from sender to be minted on destination domain, and emits a crosschain message with additional hook data appended. In addition to the standard depositForBurn parameters, depositForBurnWithHook accepts a dynamic-length hookData parameter, allowing you to include additional metadata that can trigger custom logic on the destination blockchain.

Parameters

Field	Type	Description
`amount`	`uint256`	Amount of tokens to burn
`destinationDomain`	`uint32`	Destination domain to send the message to
`mintRecipient`	`bytes32`	Address of mint recipient on destination domain (must be converted to 32 byte array, that is, prefix with zeros if needed)
`burnToken`	`address`	Address of contract to burn deposited tokens on local domain
`destinationCaller`	`bytes32`	Address as `bytes32` which can call `receiveMessage` on destination domain. If set to `bytes32(0)`, any address can call `receiveMessage`
`maxFee`	`uint256`	Maximum fee paid for transfer, specified in units of `burnToken`
`minFinalityThreshold`	`uint32`	Minimum finality threshold at which burn will be attested
`hookData`	`bytes`	Additional metadata attached to the attested message, used to trigger custom logic on the destination blockchain

getMinFeeAmount

Calculates and returns the minimum fee required for a given amount in a Standard Transfer. If the minimum fee (per unit of burnToken) is non-zero, the specified maxFee must be at least the returned minimum fee. Otherwise, the burn will revert onchain. Parameters

Field	Type	Description
`amount`	`uint256`	The amount used to compute the minimum fee. Must be greater than `1` if standard fee is applied

handleReceiveFinalizedMessage

Handles incoming message received by the local MessageTransmitter. For a burn message, mints the associated token to the requested recipient on the local domain. Validates the function sender is the local MessageTransmitter, and the remote sender is a registered remote TokenMessenger for remoteDomain. This method is called for messages where finalityThresholdExecuted ≥ 2000 (Standard Transfer). Parameters

Field	Type	Description
`remoteDomain`	`uint32`	The domain where the message originated from
`sender`	`bytes32`	The sender of the message (remote TokenMessenger)
`finalityThresholdExecuted`	`uint32`	Specifies the level of finality Circle signed the message with
`messageBody`	`bytes` (dynamic length)	The message body bytes

handleReceiveUnfinalizedMessage

Handles incoming message received by the local MessageTransmitter. For a burn message, mints the associated token to the requested recipient on the local domain. Similar to handleReceiveFinalizedMessage, but is called for messages which are not finalized (finalityThresholdExecuted < 2000) such as Fast Transfers. Unlike handleReceiveFinalizedMessage, handleReceiveUnfinalizedMessage processes messages with:

expirationBlock: If expirationBlock ≤ blockNumber on the destination domain, the message will revert and must be re-signed without the expiration block.
feeExecuted: If nonzero, the feeExecuted amount is minted to the feeRecipient.

Parameters

Field	Type	Description
`remoteDomain`	`uint32`	The domain where the message originated from
`sender`	`bytes32`	The sender of the message (remote TokenMessenger)
`finalityThresholdExecuted`	`uint32`	Specifies the level of finality Circle signed the message with
`messageBody`	`bytes` (dynamic length)	The message body bytes (see Message format)

MessageTransmitterV2

`receiveMessage`

Receives message on destination blockchain by passing message and attestation. Emits MessageReceived event. Messages with a given nonce can only be broadcast successfully once for a pair of domains. The message body of a valid message is passed to the specified recipient for further processing. Parameters

Field	Type	Description
`message`	`bytes`	Encoded message (see Message format)
`attestation`	`bytes`	Signed attestation received from Circle’s attestation service

Example

Solidity

// Mint USDC on destination chain
bytes memory message = attestationData.message;
bytes memory attestation = attestationData.attestation;

messageTransmitter.receiveMessage(message, attestation);

`sendMessage`

Sends a message to the recipient on the destination domain. Emits a MessageSent event which will be attested by Circle’s attestation service. Parameters

Field	Type	Description
`destinationDomain`	`uint32`	Destination domain ID to send the message to
`recipient`	`bytes32`	Address of recipient on destination domain
`destinationCaller`	`bytes32`	Address as `bytes32` which can call `receiveMessage` on destination domain. If set to `bytes32(0)`, any address can call `receiveMessage`
`minFinalityThreshold`	`uint32`	Minimum finality threshold requested. A value greater than 2000 is interpreted as 2000 (finalized). Thresholds: 1000 for Fast Transfer (confirmed), 2000 for Standard Transfer (finalized)
`messageBody`	`bytes`	application-specific message to be handled by recipient

Events

DepositForBurn

Emitted when USDC is burned on the source blockchain. Parameters

Field	Type	Indexed	Description
`nonce`	`uint64`	Yes	Unique message identifier
`burnToken`	`address`	Yes	Address of token burned
`amount`	`uint256`	No	Burn amount
`depositor`	`address`	Yes	Address of depositor
`mintRecipient`	`bytes32`	No	Mint recipient address on destination domain
`destinationDomain`	`uint32`	No	Destination domain identifier
`destinationTokenMessenger`	`bytes32`	No	Address of TokenMessenger contract on destination domain
`destinationCaller`	`bytes32`	No	Authorized caller of `receiveMessage` on destination domain
`maxFee`	`uint256`	No	Maximum fee for the transfer
`minFinalityThreshold`	`uint32`	No	Minimum finality threshold at which burn will be attested

MessageSent

Emitted when a message is sent from the source blockchain. Parameters

Field	Type	Indexed	Description
`message`	`bytes`	No	Raw bytes of message

MessageReceived

Emitted when a message is received on the destination blockchain. Parameters

Field	Type	Indexed	Description
`caller`	`address`	Yes	Address that called `receiveMessage`
`sourceDomain`	`uint32`	Yes	Source domain identifier
`nonce`	`uint64`	Yes	Unique message identifier
`sender`	`bytes32`	No	Address of message sender on source domain
`messageBody`	`bytes`	No	Message body

MintAndWithdraw

Emitted when USDC is minted on the destination blockchain. Parameters

Field	Type	Indexed	Description
`mintRecipient`	`address`	Yes	Address receiving minted USDC
`amount`	`uint256`	No	Amount minted
`mintToken`	`address`	Yes	Address of token minted

Bridge Kit

CCTP

Gateway

EVM Contract Interfaces

Contract responsibilities

TokenMessengerV2

depositForBurn

depositForBurnWithHook

getMinFeeAmount

handleReceiveFinalizedMessage

handleReceiveUnfinalizedMessage

MessageTransmitterV2

`receiveMessage`

`sendMessage`

Events

DepositForBurn

MessageSent

MessageReceived

MintAndWithdraw

Bridge Kit

CCTP

Gateway

​Contract responsibilities

​TokenMessengerV2

​depositForBurn

​depositForBurnWithHook

​getMinFeeAmount

​handleReceiveFinalizedMessage

​handleReceiveUnfinalizedMessage

​MessageTransmitterV2

​receiveMessage

​sendMessage

​Events

​DepositForBurn

​MessageSent

​MessageReceived

​MintAndWithdraw

Contract responsibilities

TokenMessengerV2

depositForBurn

depositForBurnWithHook

getMinFeeAmount

handleReceiveFinalizedMessage

handleReceiveUnfinalizedMessage

MessageTransmitterV2

`receiveMessage`

`sendMessage`

Events

DepositForBurn

MessageSent

MessageReceived

MintAndWithdraw