web3_sha3 - Ethereum

Example code for the web3_sha3 JSON RPC method. Сomplete guide on how to use web3_sha3 JSON RPC in GetBlock Web3 documentation.

This method returns the Keccak-256 (SHA3-256) hash of the given hex-encoded data. Commonly used to compute event signature topics, function selectors, and content-addressable identifiers off-chain in a way that's guaranteed to match on-chain behavior.

Parameters

Parameter	Type	Required	Description
data	string	Yes	Hex-encoded data to hash (with 0x prefix)

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": "web3_sha3",
    "params": [
        "0x68656c6c6f20776f726c64"
    ],
    "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: 'web3_sha3',
    params: [
        "0x68656c6c6f20776f726c64"
    ],
    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': 'web3_sha3',
        'params': [
        "0x68656c6c6f20776f726c64"
    ],
        '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": "web3_sha3",
            "params": [
        "0x68656c6c6f20776f726c64"
    ],
            "id": "getblock.io"
        }))
        .send()
        .await?
        .json::<Value>()
        .await?;
    
    println!("Result: {}", response["result"]);
    Ok(())
}

Response

{
    "jsonrpc": "2.0",
    "id": "getblock.io",
    "result": "0x47173285a8d7341e5e972fc677286384f802f8ef42a5ec5f03bbfa254cb01fad"
}

Response Parameters

Parameter	Type	Description
jsonrpc	string	JSON-RPC protocol version ("2.0")
id	string	Request identifier matching the request
result	string	Keccak-256 hash of the input data, hex-encoded (32 bytes)

Use Cases

• Event Signature Hashing: Compute the keccak256 hash of an event signature (e.g. Transfer(address,address,uint256)) to derive its topic0 for log filtering

• Function Selector Derivation: Compute the 4-byte function selector from a canonical signature for ABI encoding

• ENS Name Hashing: Hash ENS labels as part of computing an ENS namehash off-chain

• Content Addressing: Generate deterministic hashes for use as identifiers in IPFS-adjacent workflows or Merkle tree construction

Error Handling

Error Code	Message	Description
-32602	Invalid params	Input is not a valid hex-encoded string
-32603	Internal error	Node hashing subsystem returned an error

Web3 Integration

Ethers.js

ethers-example.js

import { ethers } from 'ethers';

// Ethers.js v6 exposes keccak256 directly — no RPC round-trip needed for
// off-chain hashing. This is the recommended path.
const hash = ethers.keccak256('0x68656c6c6f20776f726c64');
console.log(hash);

// For RPC-parity verification against the node:
const provider = new ethers.JsonRpcProvider('https://shared.eu-central-1.getblock.io/<ACCESS-TOKEN>/');
const nodeHash = await provider.send('web3_sha3', ['0x68656c6c6f20776f726c64']);
console.log(nodeHash);

Viem

viem-example.js

import { createPublicClient, http, keccak256 } from 'viem';
import { mainnet } from 'viem/chains';

// Viem exposes keccak256 directly — no RPC round-trip needed.
const hash = keccak256('0x68656c6c6f20776f726c64');
console.log(hash);

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

const nodeHash = await client.request({
    method: 'web3_sha3',
    params: ['0x68656c6c6f20776f726c64'],
});
console.log(nodeHash);