> For the complete documentation index, see [llms.txt](https://docs.getblock.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.getblock.io/api-reference/optimism-op/optimism_web3_sha3.md).

# 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
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.

## 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, and the optional `goal` query parameter:

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

`ask` is the immediate question: it should be specific, self-contained, and written in natural language.
`goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal.

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.