eth_call - Ethereum

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

This method executes a message call immediately against the current state without creating a transaction on the blockchain. It's the primary method for reading data from smart contracts — including token balances, contract state, and view/pure function results — and for simulating transactions before broadcasting.

Parameters

Parameter	Type	Required	Description
transaction	object	Yes	Transaction call object (see below)
blockParameter	string	Yes	Block number in hex, or latest, earliest, pending, finalized, safe
stateOverride	object	No	Optional state overrides applied before executing the call (advanced simulation)

Transaction Object

Field	Type	Required	Description
from	string	No	20-byte sender address
to	string	Yes	20-byte recipient/contract address
gas	string	No	Gas limit for the call (hex)
gasPrice	string	No	Gas price in wei (hex, legacy)
maxFeePerGas	string	No	EIP-1559 max fee per gas (hex)
maxPriorityFeePerGas	string	No	EIP-1559 priority fee per gas (hex)
value	string	No	Value to send in wei (hex)
data	string	No	Encoded function call data

Request

cURL

curl --location --request POST 'https://shared.eu-central-1.getblock.io/<ACCESS-TOKEN>/' \
--header 'Content-Type: application/json' \
--data-raw '{
    "jsonrpc": "2.0",
    "method": "eth_call",
    "params": [
        {
            "to": "0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2",
            "data": "0x70a08231000000000000000000000000d8da6bf26964af9d7eed9e03e53415d37aa96045"
        },
        "latest"
    ],
    "id": "getblock.io"
}'

Axios

example.js

const axios = require('axios');

const response = await axios.post('https://shared.eu-central-1.getblock.io/<ACCESS-TOKEN>/', {
    jsonrpc: '2.0',
    method: 'eth_call',
    params: [
        {
            "to": "0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2",
            "data": "0x70a08231000000000000000000000000d8da6bf26964af9d7eed9e03e53415d37aa96045"
        },
        "latest"
    ],
    id: 'getblock.io'
}, {
    headers: { 'Content-Type': 'application/json' }
});

console.log(response.data.result);

Request

example.py

import requests

response = requests.post(
    'https://shared.eu-central-1.getblock.io/<ACCESS-TOKEN>/',
    headers={'Content-Type': 'application/json'},
    json={
        'jsonrpc': '2.0',
        'method': 'eth_call',
        'params': [
        {
            "to": "0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2",
            "data": "0x70a08231000000000000000000000000d8da6bf26964af9d7eed9e03e53415d37aa96045"
        },
        "latest"
    ],
        'id': 'getblock.io'
    }
)

print(response.json())

Rust

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://shared.eu-central-1.getblock.io/<ACCESS-TOKEN>/")
        .header("Content-Type", "application/json")
        .json(&json!({
            "jsonrpc": "2.0",
            "method": "eth_call",
            "params": [
        {
            "to": "0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2",
            "data": "0x70a08231000000000000000000000000d8da6bf26964af9d7eed9e03e53415d37aa96045"
        },
        "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")
id	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 via balanceOf(address)

• Contract State: Read public state variables and view/pure function results from smart contracts

• Price Feeds: Query Chainlink oracle prices, Uniswap pool prices, or other DeFi rate sources

• NFT Metadata: Read ownerOf, tokenURI, and other ERC-721/ERC-1155 metadata

• DeFi Position Snapshots: Query pool reserves, exchange rates, liquidation health factors

• Simulation Before Send: Test a transaction against current state to detect reverts before broadcasting

Error Handling

Error Code	Message	Description
-32602	Invalid params	Transaction object or block parameter is malformed
3	Execution reverted	The contract call reverted — decode the return data as an Error(string) or custom error to inspect the reason
-32000	Execution error	Insufficient gas, out-of-gas, or other EVM execution failure
-32603	Internal error	Node failed to execute the call

Web3 Integration

Ethers.js

ethers-example.js

import { ethers } from 'ethers';

const provider = new ethers.JsonRpcProvider('https://shared.eu-central-1.getblock.io/<ACCESS-TOKEN>/');

// High-level: use a Contract instance for typed reads
const WETH_ABI = ['function balanceOf(address) view returns (uint256)'];
const weth = new ethers.Contract('0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2', WETH_ABI, provider);
const balance = await weth.balanceOf('0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045');
console.log('WETH balance:', ethers.formatEther(balance));

Viem

viem-example.js

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

const client = createPublicClient({
    chain: mainnet,
    transport: http('https://shared.eu-central-1.getblock.io/<ACCESS-TOKEN>/'),
});

// High-level: readContract with typed ABI
const balance = await client.readContract({
    address: '0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2',
    abi: [{ name: 'balanceOf', type: 'function', stateMutability: 'view', inputs: [{ type: 'address' }], outputs: [{ type: 'uint256' }] }],
    functionName: 'balanceOf',
    args: ['0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045'],
});
console.log('WETH balance:', formatEther(balance));