# web3\_sha3 - Optimism

This method computes and returns the Keccak-256 hash (NOT standard SHA3-256) of the input data. Keccak-256 is the hash function used throughout Ethereum and Optimism to compute addresses, transaction hashes, and other cryptographic values. The input must be a hexadecimal string.

### Parameters

| Parameter | Type | Description                                | Required |
| --------- | ---- | ------------------------------------------ | -------- |
| data      | DATA | The data to hash, as a hexadecimal string. | Yes      |

### Request Sample

{% tabs %}
{% tab title="cURL" %}
{% code title="cURL" %}

```bash
curl --location --request POST 'https://go.getblock.io/<ACCESS-TOKEN>/' \
--header 'Content-Type: application/json' \
--data-raw '{
    "jsonrpc": "2.0",
    "method": "web3_sha3",
    "params": ["0x68656c6c6f"],
    "id": "getblock.io"
}'
```

{% endcode %}
{% endtab %}

{% tab title="Axios" %}
{% code title="JavaScript (Axios)" %}

```javascript
const axios = require('axios');

const url = 'https://go.getblock.io/<ACCESS-TOKEN>/';

// "hello world" in hex
const payload = {
    jsonrpc: '2.0',
    method: 'web3_sha3',
    params: ['0x68656c6c6f'],
    id: 'getblock.io'
};

axios.post(url, payload, {
    headers: { 'Content-Type': 'application/json' }
})
.then(response => console.log('Hash:', response.data.result))
.catch(error => console.error(error));
```

{% endcode %}
{% endtab %}

{% tab title="Python" %}
{% code title="Python" overflow="wrap" %}

```python
import requests

url = "https://go.getblock.io/<ACCESS-TOKEN>/"

payload = {
    "jsonrpc": "2.0",
    "method": "web3_sha3",
    "params": ["0x68656c6c6f"],
    "id": "getblock.io"
}

response = requests.post(url, headers={"Content-Type": "application/json"}, json=payload)
print(f"Hash: {response.json()['result']}")
```

{% endcode %}
{% endtab %}

{% tab title="Rust" %}
{% code title="Rust" %}

```rust
use reqwest::Client;
use serde_json::json;

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    let client = Client::new();
    
    let payload = json!({
        "jsonrpc": "2.0",
        "method": "web3_sha3",
        "params": ["0x68656c6c6f"],
        "id": "getblock.io"
    });

    let response = client
        .post("https://go.getblock.io/<ACCESS-TOKEN>/")
        .header("Content-Type", "application/json")
        .json(&payload)
        .send()
        .await?;

    let result: serde_json::Value = response.json().await?;
    println!("{:#?}", result);
    
    Ok(())
}
```

{% endcode %}
{% endtab %}
{% endtabs %}

### Response

A successful response returns the following:

```json
{
    "jsonrpc": "2.0",
    "id": "getblock.io",
    "result": "0x1c8aff950685c2ed4bc3174f3472287b56d9517b9c948127319a09a7a36deac8"
}
```

### Response Parameters

* **`id`**: A unique request identifier, matching the `id` sent in the request body.
* **`jsonrpc`**: Specifies the use of JSON-RPC version 2.0.
* **`result`**: The Keccak-256 hash of the input data as a 32-byte hexadecimal string.

### Use Case

The web3\_sha3 method is commonly used for:

* **Data hashing**
* **Signature verification**
* **Address computation**
* **Cryptographic operations**

## Error Handling

| Error Code | Description                    |
| ---------- | ------------------------------ |
| -32602     | Invalid params - malformed hex |
| -32603     | Internal error                 |

## Web3 Integration

{% tabs %}
{% tab title="Ethers.js" %}
{% code title="Ethers.js" %}

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

// Compute keccak256 locally
const hash = ethers.keccak256(ethers.toUtf8Bytes('hello world'));
console.log('Hash:', hash);
```

{% endcode %}
{% endtab %}

{% tab title="Viem" %}
{% code title="Viem" %}

```javascript
import { keccak256, toHex } from 'viem';

const hash = keccak256(toHex('hello world'));
console.log('Hash:', hash);
```

{% endcode %}
{% endtab %}
{% endtabs %}


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://docs.getblock.io/api-reference/optimism-op/optimism_web3_sha3.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.