eth_getCode - Ethereum

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

This method returns the deployed bytecode at a specific address, hex-encoded. For contract addresses it returns the runtime bytecode; for EOAs it returns 0x. Post-Pectra (EIP-7702) EOAs can temporarily delegate to smart-contract code, in which case this returns the delegated code marker (0xef0100 + implementation address).

Parameters

Parameter	Type	Required	Description
address	string	Yes	20-byte address to query (hex-encoded with 0x prefix)
blockParameter	string	Yes	Block number in hex, or latest, earliest, pending, finalized, safe

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_getCode",
    "params": [
        "0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2",
        "latest"
    ],
    "id": "getblock.io"
}'

Axios

const axios = require('axios');

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

console.log(response.data.result);

Request

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_getCode',
        'params': [
        "0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2",
        "latest"
    ],
        'id': 'getblock.io'
    }
)

print(response.json())

Rust

use reqwest::Client;
use serde_json::{json, Value};

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    let client = Client::new();
    
    const response = client
        .post("https://shared.eu-central-1.getblock.io/<ACCESS-TOKEN>/")
        .header("Content-Type", "application/json")
        .json(&json!({
            "jsonrpc": "2.0",
            "method": "eth_getCode",
            "params": [
        "0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2",
        "latest"
    ],
            "id": "getblock.io"
        }))
        .send()
        .await?
        .json::<Value>()
        .await?;
    
    println!("Result: {}", response["result"]);
    Ok(())
}

Response

{
    "jsonrpc": "2.0",
    "id": "getblock.io",
    "result": "0x6060604052361561015a5763ffffffff7c010000000000000000000000000000000000000000000000000000000060003504166306fdde0381146101a0578063095ea7b31461022a57806318160ddd1461024b57806323b872dd1461025457806326782247146102db578063313ce56714610304578063352389f31461030d5780633950935114610319578063452a9320146103375780635c60da1b1461034057806361d027b31461034957806366188463146103525780636352211e1461037057806366188463146103b25780636352211e146103d05780636db27d5c146103e457806370a0823114610411575050"
}

Response Parameters

Parameter	Type	Description
jsonrpc	string	JSON-RPC protocol version ("2.0")
id	string	Request identifier matching the request
result	string	Hex-encoded contract runtime bytecode. 0x for EOAs. Post-Pectra: 0xef0100... for delegated EOAs (EIP-7702)

Use Cases

• Contract Existence Check: Detect whether an address is a contract (non-empty code) or an EOA (0x)

• EIP-7702 Delegation Detection: Detect when an EOA has delegated to smart-contract code by checking for the 0xef0100 prefix (post-Pectra)

• Contract Verification: Compare deployed bytecode against expected/compiled bytecode to detect tampering

• Bytecode Analysis: Feed contract bytecode into tools like evm-disassembler, heimdall, or Panoramix for reverse engineering

Error Handling

Error Code	Message	Description
-32602	Invalid params	Address is malformed, or block parameter is invalid
-32603	Internal error	Node failed to look up account state at the requested block

Web3 Integration

Ethers.js

import { ethers } from 'ethers';

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

const code = await provider.getCode('0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2');

if (code === '0x') {
    console.log('EOA (no contract code)');
} else if (code.startsWith('0xef0100')) {
    // EIP-7702: EOA has delegated to a smart contract
    const delegateAddr = '0x' + code.slice(8);
    console.log('EIP-7702 delegated EOA — delegate:', delegateAddr);
} else {
    console.log('Contract, bytecode length:', (code.length - 2) / 2, 'bytes');
}

Viem

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

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

const code = await client.getCode({ address: '0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2' });

if (!code || code === '0x') {
    console.log('EOA (no contract code)');
} else if (code.startsWith('0xef0100')) {
    const delegateAddr = '0x' + code.slice(8);
    console.log('EIP-7702 delegated EOA — delegate:', delegateAddr);
} else {
    console.log('Contract, bytecode length:', (code.length - 2) / 2, 'bytes');
}