eth_chainId - Base

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

The eth_chainId method returns the chain ID of the Base network. This value is essential for EIP-155 transaction signing to prevent replay attacks across different networks. Base mainnet uses chain ID 8453.

Parameters

• None

Request

cURL

cURL

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"
}'

Axios (JavaScript)

axios.js

const axios = require('axios');

const response = await axios.post('https://go.getblock.io/<ACCESS-TOKEN>/', {
    jsonrpc: '2.0',
    method: 'eth_chainId',
    params: [],
    id: 'getblock.io'
}, {
    headers: { 'Content-Type': 'application/json' }
});

console.log('Chain ID:', parseInt(response.data.result, 16));

Requests (Python)

requests.py

import requests

response = requests.post(
    'https://go.getblock.io/<ACCESS-TOKEN>/',
    headers={'Content-Type': 'application/json'},
    json={
        'jsonrpc': '2.0',
        'method': 'eth_chainId',
        'params': [],
        'id': 'getblock.io'
    }
)

result = response.json()
chain_id = int(result['result'], 16)
print(f'Chain ID: {chain_id}')

Rust

main.rs

use reqwest::Client;
use serde_json::{json, Value};

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    let client = Client::new();
    
    let response = client
        .post("https://go.getblock.io/<ACCESS-TOKEN>/")
        .header("Content-Type", "application/json")
        .json(&json!({
            "jsonrpc": "2.0",
            "method": "eth_chainId",
            "params": [],
            "id": "getblock.io"
        }))
        .send()
        .await?
        .json::<Value>()
        .await?;
    
    println!("Chain ID: {}", response["result"]);
    Ok(())
}

Response

response.json

{
    "jsonrpc": "2.0",
    "id": "getblock.io",
    "result": "0x2105"
}

Response Parameters

Parameter	Type	Description
jsonrpc	string	JSON-RPC protocol version ("2.0")
id	string	Request identifier matching the request
result	string	Hexadecimal chain ID (0x2105 = 8453 for Base mainnet)

Chain ID Reference

Network	Chain ID (Decimal)	Chain ID (Hex)
Base Mainnet	8453	0x2105
Base Sepolia	84532	0x14A34

Use Cases

• Network Verification: Confirm connection to the correct network before transactions

• Transaction Signing: Include chain ID in EIP-155 signatures to prevent replay attacks

• Multi-Chain Applications: Route transactions to appropriate networks

• Wallet Integration: Verify network configuration matches expected chain

• Smart Contract Deployment: Ensure deployment targets the intended network

Error Handling

Error Code	Message	Description
-32603	Internal error	Node internal failure
-32600	Invalid request	Malformed JSON-RPC request

Web3 Integration

Ethers.js (v6)

ethers.js

const { ethers } = require('ethers');

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

async function getChainId() {
    const network = await provider.getNetwork();
    console.log('Chain ID:', network.chainId);
    console.log('Network Name:', network.name);
    return network.chainId;
}

getChainId();

Viem

viem.js

import { createPublicClient, http } from 'viem';
import { base } from 'viem/chains';

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

async function getChainId() {
    const chainId = await client.getChainId();
    console.log('Chain ID:', chainId);
    return chainId;
}

getChainId();