eth_call - Polygon

Example code for the eth_call json-rpc method. Сomplete guide on how to use eth_call json-rpc in GetBlock.io Web3 documentation.

The eth_call 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 other view/pure functions. The call is executed against the state at the specified block.

Parameters

Parameter	Type	Required	Description
transaction	object	Yes	Transaction call object
blockParameter	string	Yes	Block number in hex, or "latest", "earliest", "pending", "safe", "finalized"

Transaction Object

Field	Type	Required	Description
from	string	No	The address the transaction is sent from
to	string	Yes	The contract address to call
gas	string	No	Gas limit for the call (hex)
gasPrice	string	No	Gas price in wei (hex)
value	string	No	Value to send in wei (hex)
data	string	No	Encoded function call data

Request

First Tab

cURL

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": "0x7D1AfA7B718fb893dB30A3aBc0Cfc608AaCfeBB0",
        "data": "0x70a082310000000000000000000000005aAeb6053F3E94C9b9A09f33669435E7Ef1BeAed"
    }, "latest"],
    "id": "getblock.io"
}'

Axios

Request

Rust

Response

{
    "jsonrpc": "2.0",
    "id": "getblock.io",
    "result": "0x0000000000000000000000000000000000000000000000056bc75e2d63100000"
}

Response Parameters

Field	Type	Description
jsonrpc	string	JSON-RPC version (2.0)
id	string	Request identifier
result	string	The return value of the executed contract function (hex-encoded)

Use Case

The eth_call method is essential for:

• Reading token balances: Query ERC-20/ERC-721 token balances

• Contract state queries: Read any public/external view or pure function

• Simulating transactions: Test transaction outcomes before sending

• Price feeds: Query oracle contracts for current prices

• DEX quotes: Get swap quotes from decentralized exchanges

Example: Reading ERC-20 Token Balance

JavaScript (ethers)

import { ethers } from 'ethers';

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

// ERC-20 balanceOf function selector: 0x70a08231
const tokenAddress = '0x7D1AfA7B718fb893dB30A3aBc0Cfc608AaCfeBB0'; // MATIC token
const walletAddress = '0x5aAeb6053F3E94C9b9A09f33669435E7Ef1BeAed';

// Encode the function call
const iface = new ethers.Interface(['function balanceOf(address) view returns (uint256)']);
const data = iface.encodeFunctionData('balanceOf', [walletAddress]);

const result = await provider.call({
    to: tokenAddress,
    data: data
});

const balance = ethers.getBigInt(result);
console.log('Token Balance:', ethers.formatEther(balance));

Error Handling

Status Code	Error Message	Cause
403	Forbidden	Missing or invalid ACCESS-TOKEN
-32000	execution reverted	Contract execution failed
-32000	insufficient funds	Simulated transaction requires more value
-32602	Invalid params	Invalid transaction object or block parameter

Web3 Integration

Ethers.js

JavaScript (ethers)

import { ethers } from 'ethers';

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

// Direct call
const result = await provider.call({
    to: '0x7D1AfA7B718fb893dB30A3aBc0Cfc608AaCfeBB0',
    data: '0x70a082310000000000000000000000005aAeb6053F3E94C9b9A09f33669435E7Ef1BeAed'
});
console.log('Result:', result);

// Using Contract interface (recommended)
const abi = ['function balanceOf(address) view returns (uint256)'];
const contract = new ethers.Contract('0x7D1AfA7B718fb893dB30A3aBc0Cfc608AaCfeBB0', abi, provider);
const balance = await contract.balanceOf('0x5aAeb6053F3E94C9b9A09f33669435E7Ef1BeAed');
console.log('Balance:', balance.toString());

Viem