eth_chainId - Tempo

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

Returns the chain ID of the connected network. For Tempo mainnet the result is 0x1079 (4217 in decimal); for the Moderato testnet, it is 0xa59f (42431). Chain ID is required for EIP-155 signed transactions to prevent replay attacks across chains.

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": "0x1079"
}

Response Parameters

Field

Type

Description

result

string

Chain ID in hexadecimal (0x1079 = 4217 mainnet, 0xa59f = 42431 Moderato testnet)

Use Cases

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

Error Handling

Status Code

Error Message

Cause

403

Forbidden

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>/');

const result = await provider.send('eth_chainId', []);
console.log(result);

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

// Tempo is not yet in viem/chains as a built-in — define it inline.
const tempo = defineChain({
    id: 4217,
    name: 'Tempo',
    network: 'tempo',
    // Tempo has no native gas token. The `nativeCurrency` field is required by viem's
    // type system; values shown here are a no-op placeholder — actual fees are paid in TIP-20.
    nativeCurrency: { name: 'USD Placeholder', symbol: 'USD', decimals: 18 },
    rpcUrls: {
        default: { http: ['https://go.getblock.io/<ACCESS-TOKEN>/'] }
    },
    blockExplorers: { default: { name: 'Tempo Explorer', url: 'https://explore.tempo.xyz' } }
});

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

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

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