debug_traceBlock - Ethereum

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

This method traces the execution of every transaction in a block, given the block's RLP-encoded bytes. Returns per-transaction execution traces including internal calls, state changes, and opcode-level operations depending on the tracer used. The RLP-input variant is useful for tracing hypothetical blocks not present in the local chain. Requires the debug module (Dedicated Node tier).

Parameters

Parameter	Type	Required	Description
blockRlp	string	Yes	Hex-encoded RLP of the block to trace
tracerOptions	object	No	Trace configuration — {tracer, timeout, tracerConfig} (see below)

Tracer Options

Field	Type	Required	Description
tracer	string	No	Tracer name — callTracer, prestateTracer, 4byteTracer, opcodeTracer, or a JS/WASM tracer script
timeout	string	No	Trace timeout as a duration string (10s, 1m). Defaults to 5s
tracerConfig	object	No	Tracer-specific configuration passed to the tracer

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": "debug_traceBlock",
    "params": [
        "0xf90211a0abcd...",
        {
            "tracer": "callTracer"
        }
    ],
    "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: 'debug_traceBlock',
    params: [
        "0xf90211a0abcd...",
        {
            "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.eu-central-1.getblock.io/<ACCESS-TOKEN>/',
    headers={'Content-Type': 'application/json'},
    json={
        'jsonrpc': '2.0',
        'method': 'debug_traceBlock',
        'params': [
        "0xf90211a0abcd...",
        {
            "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.eu-central-1.getblock.io/<ACCESS-TOKEN>/")
        .header("Content-Type", "application/json")
        .json(&json!({
            "jsonrpc": "2.0",
            "method": "debug_traceBlock",
            "params": [
        "0xf90211a0abcd...",
        {
            "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": "0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2",
            "value": "0x0",
            "gas": "0x186a0",
            "gasUsed": "0x8ba0",
            "input": "0x70a08231000000000000000000000000d8da6bf26964af9d7eed9e03e53415d37aa96045",
            "output": "0x0000000000000000000000000000000000000000000000000de0b6b3a7640000",
            "calls": []
        }
    ]
}

Response Parameters

Parameter	Type	Description
jsonrpc	string	JSON-RPC protocol version ("2.0")
id	string	Request identifier matching the request
result	array	Array of per-transaction traces — shape depends on the tracer used

Use Cases

• Historical Block Replay: Trace hypothetical blocks (e.g. from another fork) for what-if analysis

• Consensus-Client Testing: Feed hand-crafted RLP blocks into a tracer to test EVM implementations

• Analytics Backfill: Trace blocks captured from a peer's gossip to reconstruct execution history

Error Handling

Error Code	Message	Description
-32601	Method not found	debug module not enabled — Dedicated Node tier required
-32602	Invalid params	Block RLP is malformed or tracer options are invalid
-32603	Internal error	Node failed to execute the trace

Web3 Integration

Ethers.js

ethers-example.js

import { ethers } from 'ethers';

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

const traces = await provider.send('debug_traceBlock', [
    '0xf90211a0abcd...',  // RLP-encoded block
    { tracer: 'callTracer' }
]);
console.log('Traces:', traces.length);

Viem

viem-example.js

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

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

const traces = await client.request({
    method: 'debug_traceBlock',
    params: ['0xf90211a0abcd...', { tracer: 'callTracer' }],
});
console.log('Traces:', traces.length);