eth_chainId - ARC

Example code for the eth_chainId JSON-RPC method. Complete guide on how to use eth_chainId JSON-RPC in GetBlock Web3 documentation.

This method returns the chain ID of the connected network. For Arc testnet, the result is 0x4cef52 (5042002 in decimal). Chain ID is used in EIP-155 signed transactions to prevent replay attacks across chains and is the canonical fingerprint for Arc.

Parameters

None

Request Example

curl --location --request POST 'https://go.getblock.io/<ACCESS-TOKEN>/' \
--header 'Content-Type: application/json' \
--data-raw '{
    "jsonrpc": "2.0",
    "method": "eth_chainId",
    "params": [],
    "id": "getblock.io"
}'

import requests
import json

url = "https://go.getblock.io/<ACCESS-TOKEN>/"

payload = json.dumps({
    "jsonrpc": "2.0",
    "method": "eth_chainId",
    "params": [],
    "id": "getblock.io"
})

headers = {
    'Content-Type': 'application/json'
}

response = requests.post(url, headers=headers, data=payload)
print(response.text)

use reqwest::Client;
use serde_json::json;

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    let client = Client::new();

    let payload = json!({
        "jsonrpc": "2.0",
        "method": "eth_chainId",
        "params": [],
        "id": "getblock.io"
});

    let response = client
        .post("https://go.getblock.io/<ACCESS-TOKEN>/")
        .header("Content-Type", "application/json")
        .json(&payload)
        .send()
        .await?;

    let result: serde_json::Value = response.json().await?;
    println!("{:#?}", result);

    Ok(())
}

Response Example

{
    "jsonrpc": "2.0",
    "id": "getblock.io",
    "result": "0x4cef52"
}

Response Parameters

Field

Type

Description

result

string

Chain ID in hexadecimal (0x4cef52 = 5042002 testnet; mainnet chain ID not yet published)

Use Cases

Constructing EIP-155 signed transactions
Validating that a wallet is connected to Arc rather than another EVM chain
Multi-chain dApps that branch logic by chain ID
Configuring transaction signers in Ethers.js / Viem

Error Handling

Status Code

Error Message

Cause

403

Forbidden

Missing or invalid <ACCESS-TOKEN>

-32602

Invalid params

Request parameters are missing or malformed

-32601

Method not found

The method is not supported by this node

429

Too Many Requests

Rate limit exceeded for your plan

SDK Integration

import { ethers } from 'ethers';

const provider = new ethers.JsonRpcProvider('https://go.getblock.io/<ACCESS-TOKEN>/');

// Most methods are exposed directly on the provider.
// For raw access, use provider.send(method, params).
const result = await provider.send('eth_chainId', []);
console.log(result);

import { createPublicClient, http, defineChain } from 'viem';

const arcTestnet = defineChain({
    id: 5042002,
    name: 'Arc Testnet',
    network: 'arc-testnet',
    nativeCurrency: { name: 'USD Coin', symbol: 'USDC', decimals: 6 },
    rpcUrls: { default: { http: ['https://go.getblock.io/<ACCESS-TOKEN>/'] } },
    blockExplorers: { default: { name: 'arcscan', url: 'https://testnet.arcscan.app' } }
});

const client = createPublicClient({
    chain: arcTestnet,
    transport: http('https://go.getblock.io/<ACCESS-TOKEN>/')
});

const result = await client.request({ method: 'eth_chainId', params: [] });
console.log(result);

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