debug_traceCall - GIWA

Example code for the debug_traceCall JSON-RPC method. Complete guide on how to use debug_traceCall JSON-RPC in GetBlock Web3 documentation.

This method traces a simulated message call against a given block without submitting a transaction, returning a detailed execution trace. It is a Dedicated Node tier method.

This method belongs to the debug namespace and is available on GetBlock Dedicated Nodes only. It is not served on shared endpoints.

Parameters

Parameter	Type	Required	Description
transaction	object	Yes	Transaction call object
blockParameter	string	Yes	Block number in hex, or "latest"
options	object	No	Tracer options (e.g. callTracer)

Transaction Object

Field	Type	Required	Description
from	string	No	20-byte sender address
to	string	Yes	20-byte recipient/contract address
data	string	No	Encoded function call data

Request

cURL

curl --location --request POST 'https://shared.ap-southeast-1.getblock.io/<ACCESS-TOKEN>/' \
--header 'Content-Type: application/json' \
--data-raw '{
    "jsonrpc": "2.0",
    "method": "debug_traceCall",
    "params": [{ "from": "0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045", "to": "0x4200000000000000000000000000000000000006", "data": "0x70a08231000000000000000000000000d8da6bf26964af9d7eed9e03e53415d37aa96045" }, "latest", { "tracer": "callTracer" }],
    "id": "getblock.io"
}'

Axios

example.js

const axios = require('axios');

const response = await axios.post('https://shared.ap-southeast-1.getblock.io/<ACCESS-TOKEN>/', {
    jsonrpc: '2.0',
    method: 'debug_traceCall',
    params: [{ from: '0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045', to: '0x4200000000000000000000000000000000000006', data: '0x70a08231000000000000000000000000d8da6bf26964af9d7eed9e03e53415d37aa96045' }, 'latest', { tracer: 'callTracer' }],
    id: 'getblock.io'
}, {
    headers: { 'Content-Type': 'application/json' }
});

console.log(response.data.result);

Request

example.py

import requests

response = requests.post(
    'https://shared.ap-southeast-1.getblock.io/<ACCESS-TOKEN>/',
    headers={'Content-Type': 'application/json'},
    json={
        'jsonrpc': '2.0',
        'method': 'debug_traceCall',
        'params': [{ 'from': '0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045', 'to': '0x4200000000000000000000000000000000000006', 'data': '0x70a08231000000000000000000000000d8da6bf26964af9d7eed9e03e53415d37aa96045' }, 'latest', { 'tracer': 'callTracer' }],
        '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.ap-southeast-1.getblock.io/<ACCESS-TOKEN>/")
        .header("Content-Type", "application/json")
        .json(&json!({
            "jsonrpc": "2.0",
            "method": "debug_traceCall",
            "params": [{ "from": "0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045", "to": "0x4200000000000000000000000000000000000006", "data": "0x70a08231000000000000000000000000d8da6bf26964af9d7eed9e03e53415d37aa96045" }, "latest", { "tracer": "callTracer" }],
            "id": "getblock.io"
        }))
        .send()
        .await?
        .json::<Value>()
        .await?;

    println!("Result: {}", response["result"]);
    Ok(())
}

Response

{
    "jsonrpc": "2.0",
    "id": "getblock.io",
    "result": {
        "type": "CALL",
        "from": "0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045",
        "to": "0x4200000000000000000000000000000000000006",
        "gasUsed": "0x5208",
        "output": "0x",
        "calls": []
    }
}

Response Parameters

Parameter	Type	Description
jsonrpc	string	JSON-RPC protocol version ("2.0")
id	string	Request identifier matching the request
result	object	Execution trace of the simulated call

Use Cases

• Call Debugging: Trace a read or write call without broadcasting it

• Revert Analysis: See where a failing call reverts

• Internal Transfers: Extract nested calls and value flows

• dApp Diagnostics: Investigate contract behavior during development

Error Handling

Error Code	Message	Description
-32602	Invalid params	Malformed transaction, block parameter, or options
-32601	Method not found	The debug namespace is not enabled on this endpoint

Web3 Integration

Ethers.js

ethers-example.js

import { ethers } from 'ethers';

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

const trace = await provider.send('debug_traceCall', [{ from: '0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045', to: '0x4200000000000000000000000000000000000006', data: '0x70a08231000000000000000000000000d8da6bf26964af9d7eed9e03e53415d37aa96045' }, 'latest', { tracer: 'callTracer' }]);

Viem

viem-example.js

import { createPublicClient, http } from 'viem';

const client = createPublicClient({
  transport: http('https://shared.ap-southeast-1.getblock.io/<ACCESS-TOKEN>/')
});

const trace = await client.request({ method: 'debug_traceCall', params: [{ from: '0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045', to: '0x4200000000000000000000000000000000000006', data: '0x70a08231000000000000000000000000d8da6bf26964af9d7eed9e03e53415d37aa96045' }, 'latest', { tracer: 'callTracer' }] });