trace_transaction | Fantom


Dedicated node required

Note that a dedicaded node is requried to enable the debug and trace APIs on Fantom.

Fantom API method that traces a specific transaction. It provides a detailed record of all the steps the Ethereum Virtual Machine (EVM) took during the execution, including all the operations performed and the changes made to the blockchain state. This method is available on Erigon only.


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  • hash β€” the hash identifying a transaction


  • action β€” an object that describes the action taken by the transaction:
    • from β€” the address of the sender who initiated the transaction.
    • callType β€” the type of call, call or delegatecall, two ways to invoke a function in a smart contract. call creates a new environment for the function to work in, so changes made in that function won't affect the environment where the function was called. delegatecall doesn't create a new environment. Instead, it runs the function within the environment of the caller, so changes made in that function will affect the caller's environment.
    • gas β€” the units of gas included in the transaction by the sender.
    • input β€” the optional input data sent with the transaction, usually used to interact with smart contracts.
    • to β€” the address of the recipient of the transaction if it was a transaction to an address. For contract creation transactions, this field is null.
    • value β€” the value of the native token transferred along with the transaction, in Wei.
    • blockHash β€” the hash of the block in which the transaction was included.
    • blockNumber β€” the number of the block in which the transaction was included.
    • error β€” a string that indicates whether the transaction was successful or not. null if successful, Reverted if not.
    • result β€” an object that contains additional data about the execution of the transaction:
      • gasUsed β€” the total used gas by the call, encoded as hexadecimal.
      • output β€” the return value of the call, encoded as a hexadecimal string.
    • subtraces β€” the number of sub-traces created during execution. When a transaction is executed on the EVM, it may trigger additional sub-executions, such as when a smart contract calls another smart contract or when an external account is accessed.
    • traceAddress β€” an array that indicates the position of the transaction in the trace.
    • transactionHash β€” the hash of the transaction.
    • transactionPosition β€” the position of the transaction in the block.
    • type β€” the type of action taken by the transaction, call or create. call is the most common type of trace and occurs when a smart contract invokes another contract's function. create represents the creation of a new smart contract. This type of trace occurs when a smart contract is deployed to the blockchain.

trace_transaction code examples

const { Web3, Web3PluginBase } = require("web3");
const web3 = new Web3(NODE_URL);

// Define the TraceBlockPlugin class
class TraceBlockPlugin extends Web3PluginBase {
    pluginNamespace = 'erigon';

    async traceTransaction(txHash) {
        return this.requestManager.send({
            method: 'trace_transaction',
            params: [txHash],

// Register the plugin
web3.registerPlugin(new TraceBlockPlugin());

async function traceTransaction(txHash) {
    const result = await web3.erigon.traceTransaction(txHash);

const ethers = require('ethers');
const provider = new ethers.JsonRpcProvider(NODE_URL);

const traceTransaction = async (txHash) => {
  const traces = await provider.send("trace_transaction", [txHash]);

from web3 import Web3  
web3 = Web3.HTTPProvider(node_url)

tx_hash = "0xa2b1e35f59d184da1996b37803ed2e8e81057be7d07a93af48a410fd9338d616"

traces = web3.provider.make_request('trace_transaction', [tx_hash])

Use case

A practical use case of the trace_transaction method can inspect NFT transfers, allowing you to identify internal transactions, the sender and receiver, and the amounts transferred. This can be especially useful when analyzing an ERC-721 token purchase on a marketplace like Opensea, where funds transfer is not always straightforward due to multiple internal calls for transferring funds to the NFT owner, paying royalties to the creator, and other factors. By using trace_transaction, you can gain a more comprehensive understanding of the transaction flow.

Try the trace_transaction RPC method yourself