eth_chainId - AVAX

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

Returns the C-Chain ID. For mainnet the result is 0xa86a (43114); for Fuji testnet it is 0xa869 (43113). Required for EIP-155 signed transactions to prevent cross-chain replay.

Parameters

None

Request Example

curl --location --request POST 'https://go.getblock.io/<ACCESS-TOKEN>/ext/bc/C/rpc' \
--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>/ext/bc/C/rpc"

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>/ext/bc/C/rpc")
        .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": "0xa86a"
}

Response Parameters

Field

Type

Description

result

string

Chain ID in hexadecimal (0xa86a = 43114 mainnet, 0xa869 = 43113 Fuji testnet)

Use Cases

Constructing EIP-155 signed transactions
Validating a wallet is connected to Avalanche C-Chain
Multi-chain dApps that branch logic by chain ID

Error Handling

Status Code

Error Message

Cause

404

Not found

Missing or invalid <ACCESS-TOKEN>

-32602

Invalid params

Request parameters are missing or malformed

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>/ext/bc/C/rpc');

// 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 } from 'viem';
import { avalanche } from 'viem/chains';

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

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

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