Alchemy Login

traceTransaction - SDK

Attempts to run the transaction in the exact same manner as it was executed on the network. It will replay any transaction that may have been executed prior to this one before it and will then attempt to execute the transaction that corresponds to the given hash.

Don’t have an API key?

Start using this method in your app today.

Get started for free

Description

traceTransactionattempts to run the transaction in the exact same manner as it was executed on the network. It will replay any transaction that may have been executed prior to this one before it and will then attempt to execute the transaction that corresponds to the given hash.

Parameters

NameTypeDescriptionExample
transactionHashstringThe transaction hash of the transaction to trace.0x60e07437b027f8b64b409137f75e527583f1139741d311c6969d4efc879d94b8
tracerobjectTracer type and configuration.

This tracer tracks all call frames executed during a transaction, including depth 0. The returned result is a nested list of call frames executed as part of the call.

It is an object with the following options:

1. type: The type of tracer to use during the execution. The options are callTracer and prestateTracer

2. onlyTopCall?: Whether to only trace the main (top-level) calls and ignore sub-calls. It is a boolean and defaults to false.		{ type: callTracer, onlyTopCall: true }
timeout?stringA optional duration string of decimal numbers that overrides the default timeout of 5 seconds for JavaScript-based tracing calls. Max timeout is "10s". Valid time units are "ns", "us", "ms", "s" each with optional fraction, such as "300ms" or "2s45ms""10s", "300ms" etc.

Response

The traceTransaction method returns a response object with the following properties.

Property (Field)Description
typeThe type of call: CALL or CREATE for the top-level call.
fromFrom address of the transaction.
toTo address of the transaction.
valueAmount of value transfer as a hex string.
gasGas provided for call as a hex string.
gasUsedGas used during the call as a hex string.
inputCall data.
outputReturn data.
errror?Optional error field.
revertReason?Solidity revert reason, if the call reverted.
calls?Array of sub-calls executed as part of the original call.

Example Request and Response

Prerequisite: You will need to install the Alchemy SDK before making requests with it.

The commands for installing it using npm or yarn are given below:

npm install alchemy-sdk

yarn add alchemy-sdk

Request

Here is an example of how to make a traceTransaction request using the Alchemy SDK:

// Imports the Alchemy SDK
const { Alchemy, Network } = require("alchemy-sdk");

// Configures the Alchemy SDK
const config = {
  apiKey: "demo", // Replace with your API key
  network: Network.ETH_MAINNET, // Replace with your network
};

// Creates an Alchemy object instance with the config to use for making requests
const alchemy = new Alchemy(config);

// Example of using the traceTransaction method
const main = async () => {
  // The transaction hash of the transaction to trace.
  let txHash =
    "0x45c1b4c9685a0a9312e698ad273802c20f0354a2248f3f20bbd3623ef32f9523";

  // Tracer type and configuration.
  let tracerConfig = {
    type: "callTracer",
    onlyTopCall: true,
  };

  let timeout = "10s";

  // Calling the traceTransaction method
  let response = await alchemy.debug.traceTransaction(
    txHash,
    tracerConfig,
    timeout
  );

  // Logging the response to the console
  console.log(response);
};

main();

Response

And here is an example of what a successful response to this request might look like:

{
  type: 'CALL',
  from: '0xe5cb067e90d5cd1f8052b83562ae670ba4a211a8',
  to: '0xdac17f958d2ee523a2206206994597c13d831ec7',
  value: '0x0',
  gas: '0x11def',
  gasUsed: '0xa281',
  input: '0xa9059cbb0000000000000000000000006a3623db71c1b3442a94e3fd4655334b4811469300000000000000000000000000000000000000000000000000000000000f4240',
  output: '0x'
}

Code Sandbox

You can test the traceTransaction method using the code sandbox below:

Use Cases

Some of the use cases for traceCall are:

  • Debugging Contract Issues: Developers can use the traceTransaction method to diagnose and fix issues with smart contract execution by tracing the flow of execution and the state changes made by the contract in response to a specific transaction.

  • Optimizing Contract Performance: Developers can use the traceTransaction method to identify and optimize slow or inefficient sections of code by tracing the execution and gas consumption of a specific transaction.

  • Verifying Contract Security: Security auditors can use the traceTransaction method to verify the security of smart contracts by tracing the execution of malicious transactions and evaluating the contract's response.

Related Methods

Here are the methods related to traceTransaction:

  • traceCall: Runs an eth_call with the context of the provided block execution using the final state of the parent block as the base.

  • traceBlock: Replays a block that has already been mined.

ReadMe