> 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/zksync/debug_tracecall-zksync.md).

# debug\_traceCall - zkSync

Example code for the debug\_traceCall JSON-RPC method. Сomplete guide on how to use debug\_traceCall JSON-RPC in GetBlock.io Web3 documentation.

Traces a call at a specific block without committing it. Use the optional third parameter to specify a tracer and timeout.

## Parameters

| Parameter      | Type   | Required | Description                                    |
| -------------- | ------ | -------- | ---------------------------------------------- |
| callObject     | object | Yes      | Transaction-shaped call object                 |
| blockParameter | string | Yes      | Block at which to trace — number, hash, or tag |
| options        | object | No       | Optional tracer options                        |

## Request Example

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

```bash
curl --location --request POST 'https://shared.eu-central-1.getblock.io/<ACCESS-TOKEN>/' \
--header 'Content-Type: application/json' \
--data-raw '{
    "jsonrpc": "2.0",
    "method": "debug_traceCall",
    "params": [
        {
            "from": "0x36615cf349d7f6344891b1e7ca7c72883f5dc049",
            "to": "0xd85498dbeaeb1df24be52eed4f52eac2fbd56245",
            "data": "0x"
        },
        "latest",
        {
            "tracer": "callTracer"
        }
    ],
    "id": "getblock.io"
}'
```

{% endtab %}

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

```javascript
import axios from 'axios';

const data = JSON.stringify({
    "jsonrpc": "2.0",
    "method": "debug_traceCall",
    "params": [
        {
            "from": "0x36615cf349d7f6344891b1e7ca7c72883f5dc049",
            "to": "0xd85498dbeaeb1df24be52eed4f52eac2fbd56245",
            "data": "0x"
        },
        "latest",
        {
            "tracer": "callTracer"
        }
    ],
    "id": "getblock.io"
});

const config = {
    method: 'post',
    url: 'https://shared.eu-central-1.getblock.io/<ACCESS-TOKEN>/',
    headers: {
        'Content-Type': 'application/json'
    },
    data: data
};

axios(config)
    .then(response => console.log(JSON.stringify(response.data, null, 2)))
    .catch(error => console.log(error));
```

{% endtab %}

{% tab title="Python (Requests)" %}

```python
import requests
import json

url = "https://shared.eu-central-1.getblock.io/<ACCESS-TOKEN>/"

payload = json.dumps({
    "jsonrpc": "2.0",
    "method": "debug_traceCall",
    "params": [
        {
            "from": "0x36615cf349d7f6344891b1e7ca7c72883f5dc049",
            "to": "0xd85498dbeaeb1df24be52eed4f52eac2fbd56245",
            "data": "0x"
        },
        "latest",
        {
            "tracer": "callTracer"
        }
    ],
    "id": "getblock.io"
})

headers = {
    'Content-Type': 'application/json'
}

response = requests.post(url, headers=headers, data=payload)
print(response.text)
```

{% endtab %}

{% tab title="Rust (Reqwest)" %}

```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": "debug_traceCall",
        "params": [
                {
                        "from": "0x36615cf349d7f6344891b1e7ca7c72883f5dc049",
                        "to": "0xd85498dbeaeb1df24be52eed4f52eac2fbd56245",
                        "data": "0x"
                },
                "latest",
                {
                        "tracer": "callTracer"
                }
        ],
        "id": "getblock.io"
});

    let response = client
        .post("https://shared.eu-central-1.getblock.io/<ACCESS-TOKEN>/")
        .header("Content-Type", "application/json")
        .json(&payload)
        .send()
        .await?;

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

    Ok(())
}
```

{% endtab %}
{% endtabs %}

## Response Example

{% code overflow="wrap" %}

```json
{
    "jsonrpc": "2.0",
    "id": "getblock.io",
    "result": {
        "type": "Call",
        "from": "0x36615cf349d7f6344891b1e7ca7c72883f5dc049",
        "to": "0xd85498dbeaeb1df24be52eed4f52eac2fbd56245",
        "gas": "0x18be25",
        "gasUsed": "0x5208",
        "value": "0x0",
        "output": "0x",
        "input": "0x",
        "calls": []
    }
}
```

{% endcode %}

## Response Parameters

| Field  | Type   | Description                                                         |
| ------ | ------ | ------------------------------------------------------------------- |
| result | object | Trace object with the same shape as `debug_traceTransaction` result |

## Use Cases

* Simulating contract calls in detail before broadcast
* Off-chain backtesting of new contract interactions
* Pre-flight diagnostics for complex transactions

## Error Handling

| Status Code | Error Message     | Cause                                       |
| ----------- | ----------------- | ------------------------------------------- |
| 403         | Forbidden         | Missing or invalid `<ACCESS-TOKEN>`         |
| -32602      | Invalid params    | Request parameters are missing or malformed |
| 429         | Too Many Requests | Rate limit exceeded for your plan           |

## SDK Integration

{% tabs %}
{% tab title="zksync-ethers (JavaScript)" %}
{% code overflow="wrap" %}

```javascript
import { Provider } from 'zksync-ethers';

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

// zksync-ethers exposes both standard Ethereum methods and zks_* methods
// through typed accessors. For raw access:
const result = await provider.send('debug_traceCall', [{"from": "0x36615cf349d7f6344891b1e7ca7c72883f5dc049", "to": "0xd85498dbeaeb1df24be52eed4f52eac2fbd56245", "data": "0x"}, "latest", {"tracer": "callTracer"}]);
console.log(result);
```

{% endcode %}
{% endtab %}

{% tab title="zksync2-python (Python)" %}
{% code overflow="wrap" %}

```python
from zksync2.module.module_builder import ZkSyncBuilder

zk_web3 = ZkSyncBuilder.build('https://shared.eu-central-1.getblock.io/<ACCESS-TOKEN>/')

# zksync2-python exposes the JSON-RPC layer directly.
result = zk_web3.zksync._zks_endpoints if 'debug_traceCall'.startswith('zks_') else None
# Or call any method generically:
result = zk_web3.provider.make_request('debug_traceCall', [{"from": "0x36615cf349d7f6344891b1e7ca7c72883f5dc049", "to": "0xd85498dbeaeb1df24be52eed4f52eac2fbd56245", "data": "0x"}, "latest", {"tracer": "callTracer"}])
print(result)
```

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