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Overview

The Chain struct represents a blockchain configuration for CCTP V2. It contains all the necessary information to interact with a specific blockchain, including contract addresses, RPC endpoints, and chain-specific settings.

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Type Definition

type Chain struct {
    Name                 string
    ChainID              *big.Int
    Domain               uint32
    RPC                  string
    TokenMessengerV2     string
    MessageTransmitterV2 string
    USDC                 string
    Explorer             string
    IsTestnet            bool
    InstantFinality      bool
}

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Fields

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Name
string
required
The human-readable name of the blockchain (e.g., “Ethereum”, “Base”, “Arbitrum”)
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ChainID
*big.Int
required
The chain ID as defined in EIP-155. Used for transaction signing and network identification.
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Domain
uint32
required
The CCTP domain identifier for this chain. Each blockchain supported by CCTP has a unique domain number.
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RPC
string
required
The RPC endpoint URL for connecting to the blockchain network.
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TokenMessengerV2
string
required
The contract address of the TokenMessengerV2 contract on this chain. This contract handles USDC burning.
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MessageTransmitterV2
string
required
The contract address of the MessageTransmitterV2 contract on this chain. This contract handles message receiving and USDC minting.
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USDC
string
required
The contract address of the USDC token on this chain.
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Explorer
string
required
The base URL of the blockchain explorer (e.g., “https://etherscan.io”).
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IsTestnet
bool
required
Indicates whether this chain is a testnet (true) or mainnet (false).
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InstantFinality
bool
required
Indicates whether the chain has instant finality. Chains with instant finality don’t need Fast Transfer distinction as they already provide quick transaction finality.Examples of chains with instant finality:
  • Avalanche
  • Polygon PoS
  • Sonic
  • Sei
  • XDC
  • HyperEVM

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Usage Examples

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Getting a Chain by Domain

package main

import (
    "fmt"
    "github.com/circlefin/cctp-go"
)

func main() {
    // Get Ethereum mainnet chain by domain
    chain, err := cctp.GetChainByDomain(0, false)
    if err != nil {
        panic(err)
    }
    
    fmt.Printf("Chain: %s\n", chain.Name)
    fmt.Printf("Domain: %d\n", chain.Domain)
    fmt.Printf("RPC: %s\n", chain.RPC)
}

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Getting a Chain by Name

package main

import (
    "fmt"
    "github.com/circlefin/cctp-go"
)

func main() {
    // Get Base mainnet chain by name
    chain, err := cctp.GetChainByName("Base", false)
    if err != nil {
        panic(err)
    }
    
    fmt.Printf("Chain ID: %s\n", chain.ChainID.String())
    fmt.Printf("Domain: %d\n", chain.Domain)
    fmt.Printf("USDC Address: %s\n", chain.USDC)
}

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Getting All Chains

package main

import (
    "fmt"
    "github.com/circlefin/cctp-go"
)

func main() {
    // Get all mainnet chains
    chains := cctp.GetChains(false)
    
    for _, chain := range chains {
        fmt.Printf("%s (Domain %d)\n", chain.Name, chain.Domain)
    }
    
    // Get all testnet chains
    testnets := cctp.GetChains(true)
    
    for _, chain := range testnets {
        fmt.Printf("%s (Domain %d)\n", chain.Name, chain.Domain)
    }
}

​
Applying Custom RPC Overrides

package main

import (
    "fmt"
    "github.com/circlefin/cctp-go"
)

func main() {
    // Get all mainnet chains
    chains := cctp.GetMainnetChains()
    
    // Define custom RPC endpoints
    overrides := map[string]string{
        "Ethereum": "https://my-custom-ethereum-rpc.example.com",
        "Base":     "https://my-custom-base-rpc.example.com",
    }
    
    // Apply overrides
    customChains := cctp.ApplyRPCOverrides(chains, overrides)
    
    for _, chain := range customChains {
        fmt.Printf("%s RPC: %s\n", chain.Name, chain.RPC)
    }
}

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Checking Instant Finality

package main

import (
    "fmt"
    "github.com/circlefin/cctp-go"
)

func main() {
    chain, _ := cctp.GetChainByName("Avalanche", false)
    
    if chain.InstantFinality {
        fmt.Printf("%s has instant finality - Standard Transfer recommended\n", chain.Name)
    } else {
        fmt.Printf("%s does not have instant finality - Fast Transfer available\n", chain.Name)
    }
}
  • GetChains(testnet bool) []Chain - Returns all configured chains
  • GetMainnetChains() []Chain - Returns all mainnet chain configurations
  • GetTestnetChains() []Chain - Returns all testnet chain configurations
  • GetChainByDomain(domain uint32, testnet bool) (*Chain, error) - Returns a chain by its domain ID
  • GetChainByName(name string, testnet bool) (*Chain, error) - Returns a chain by its name
  • ApplyRPCOverrides(chains []Chain, overrides map[string]string) []Chain - Applies custom RPC URL overrides

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Supported Chains

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Mainnet Chains

Chain NameDomainChain IDInstant Finality
Ethereum01No
Avalanche143114Yes
OP Mainnet210No
Arbitrum342161No
Base68453No
Polygon PoS7137Yes
Unichain101301No
Linea1159144No
Codex125115No
Sonic13146Yes
World Chain14480No
Sei161329Yes
XDC1850Yes
HyperEVM19998Yes
Ink2157073No
Plume2298865No
All V2 mainnet chains use the same contract addresses:
  • TokenMessengerV2: 0x28b5a0e9C621a5BadaA536219b3a228C8168cf5d
  • MessageTransmitterV2: 0x81D40F21F12A8F0E3252Bccb954D722d4c464B64

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See Also

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