eth_chainId

Returns the chain ID used for transaction signing on Astar.

Why Astar? Build on Polkadot's leading dApp hub supporting EVM, WASM, and upcoming PolkaVM environments with EVM + WASM + PolkaVM support, Build2Earn developer rewards, dApp Staking, and Soneium cross-layer integration.

Use Cases

The eth_chainId method is essential for:

• Transaction signing - Ensure transactions are signed for the correct network
• Network verification - Confirm connection to the expected chain
• Multi-chain apps - Handle different networks programmatically
• Wallet integration - Validate network before transactions

Parameters

This method accepts no parameters.

Request

{
  "jsonrpc": "2.0",
  "method": "eth_chainId",
  "params": [],
  "id": 1
}

Returns

Type	Description
QUANTITY	Chain ID in hexadecimal

Response

{
  "jsonrpc": "2.0",
  "id": 1,
  "result": "0x1"
}

Code Examples

cURL

curl -X POST https://api-astar.n.dwellir.com/YOUR_API_KEY \
  -H "Content-Type: application/json" \
  -d '{
    "jsonrpc": "2.0",
    "method": "eth_chainId",
    "params": [],
    "id": 1
  }'

JavaScript

import { JsonRpcProvider } from 'ethers';

const provider = new JsonRpcProvider('https://api-astar.n.dwellir.com/YOUR_API_KEY');

const network = await provider.getNetwork();
console.log('Chain ID:', network.chainId);

// Verify network before transaction
async function verifyNetwork(expectedChainId) {
  const network = await provider.getNetwork();
  if (network.chainId !== BigInt(expectedChainId)) {
    throw new Error(`Wrong network. Expected ${expectedChainId}, got ${network.chainId}`);
  }
  return true;
}

Python

from web3 import Web3

w3 = Web3(Web3.HTTPProvider('https://api-astar.n.dwellir.com/YOUR_API_KEY'))

chain_id = w3.eth.chain_id
print(f'Chain ID: {chain_id}')

# Verify network
def verify_network(expected_chain_id):
    chain_id = w3.eth.chain_id
    if chain_id != expected_chain_id:
        raise ValueError(f'Wrong network. Expected {expected_chain_id}, got {chain_id}')
    return True

Go

package main

import (
    "context"
    "fmt"
    "log"

    "github.com/ethereum/go-ethereum/ethclient"
)

func main() {
    client, err := ethclient.Dial("https://api-astar.n.dwellir.com/YOUR_API_KEY")
    if err != nil {
        log.Fatal(err)
    }

    chainID, err := client.ChainID(context.Background())
    if err != nil {
        log.Fatal(err)
    }

    fmt.Printf("Chain ID: %d\n", chainID)
}

Related Methods

• net_version - Get network version
• eth_syncing - Check sync status