eth_call - Base

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

This method executes a new message call immediately without creating a transaction on the blockchain. This is the primary method for reading data from smart contracts, including token balances, contract state, and view/pure function results.

Parameters

Parameter

Type

Required

Description

transaction

object

Yes

Transaction call object

blockParameter

string

Yes

Block number in hex, or "latest", "earliest", "pending"

Transaction Object

Field

Type

Required

Description

from

string

20-byte sender address

string

Yes

20-byte recipient/contract address

gas

string

Gas limit for the call (hex)

gasPrice

string

Gas price in wei (hex)

value

string

Value to send in wei (hex)

data

string

Encoded function call data

Request

curl --location --request POST 'https://go.getblock.io/<ACCESS-TOKEN>/' \
--header 'Content-Type: application/json' \
--data-raw '{
    "jsonrpc": "2.0",
    "method": "eth_call",
    "params": [{
        "to": "0x4200000000000000000000000000000000000006",
        "data": "0x70a082310000000000000000000000006E0d01A76C3Cf4288372a29124A26D4353EE51BE"
    }, "latest"],
    "id": "getblock.io"
}'

example.js

const axios = require('axios');

// ERC-20 balanceOf call
const response = await axios.post('https://go.getblock.io/<ACCESS-TOKEN>/', {
    jsonrpc: '2.0',
    method: 'eth_call',
    params: [{
        to: '0x4200000000000000000000000000000000000006', // WETH on Base
        data: '0x70a082310000000000000000000000006E0d01A76C3Cf4288372a29124A26D4353EE51BE'
    }, 'latest'],
    id: 'getblock.io'
}, {
    headers: { 'Content-Type': 'application/json' }
});

const balance = parseInt(response.data.result, 16);
console.log('Token Balance:', balance / 1e18);

example.py

import requests

response = requests.post(
    'https://go.getblock.io/<ACCESS-TOKEN>/',
    headers={'Content-Type': 'application/json'},
    json={
        'jsonrpc': '2.0',
        'method': 'eth_call',
        'params': [{
            'to': '0x4200000000000000000000000000000000000006',
            'data': '0x70a082310000000000000000000000006E0d01A76C3Cf4288372a29124A26D4353EE51BE'
        }, 'latest'],
        'id': 'getblock.io'
    }
)

result = response.json()
balance = int(result['result'], 16)
print(f'Token Balance: {balance / 1e18}')

example.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_call",
            "params": [{
                "to": "0x4200000000000000000000000000000000000006",
                "data": "0x70a082310000000000000000000000006E0d01A76C3Cf4288372a29124A26D4353EE51BE"
            }, "latest"],
            "id": "getblock.io"
        }))
        .send()
        .await?
        .json::<Value>()
        .await?;
    
    println!("Result: {}", response["result"]);
    Ok(())
}

Response

{
    "jsonrpc": "2.0",
    "id": "getblock.io",
    "result": "0x0000000000000000000000000000000000000000000000000de0b6b3a7640000"
}

Response Parameters

Parameter

Type

Description

jsonrpc

string

JSON-RPC protocol version ("2.0")

string

Request identifier matching the request

result

string

Hex-encoded return data from the contract call

Use Cases

Token Balances: Query ERC-20 token balances using balanceOf
Contract State: Read public state variables from smart contracts
Price Feeds: Query oracle prices from Chainlink or other protocols
NFT Metadata: Read NFT ownership and metadata
DeFi Calculations: Query pool reserves, exchange rates, and liquidity

Error Handling

Error Code

Message

Description

-32602

Invalid params

Invalid transaction object or block parameter

-32603

Internal error

Contract execution error

Execution reverted

Contract reverted the call

-32000

Execution error

Insufficient gas or other execution failure

Web3 Integration

ethers-example.js

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

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

// Using Contract interface for type-safe calls
async function getTokenBalance(tokenAddress, walletAddress) {
    const abi = ['function balanceOf(address) view returns (uint256)'];
    const contract = new ethers.Contract(tokenAddress, abi, provider);
    
    const balance = await contract.balanceOf(walletAddress);
    console.log('Balance:', ethers.formatUnits(balance, 18));
    
    return balance;
}

// WETH on Base
getTokenBalance(
    '0x4200000000000000000000000000000000000006',
    '0x6E0d01A76C3Cf4288372a29124A26D4353EE51BE'
);

// Low-level call
async function rawCall(to, data) {
    const result = await provider.call({
        to: to,
        data: data
    });
    return result;
}

viem-example.js

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

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

// Using readContract for type-safe calls
async function getTokenBalance(tokenAddress, walletAddress) {
    const balance = await client.readContract({
        address: tokenAddress,
        abi: parseAbi(['function balanceOf(address) view returns (uint256)']),
        functionName: 'balanceOf',
        args: [walletAddress]
    });
    
    console.log('Balance:', balance);
    return balance;
}

// WETH on Base
getTokenBalance(
    '0x4200000000000000000000000000000000000006',
    '0x6E0d01A76C3Cf4288372a29124A26D4353EE51BE'
);

// Low-level call
async function rawCall(to, data) {
    const result = await client.call({
        to: to,
        data: data
    });
    return result;
}

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