trace_block | Fantom


Dedicated node required

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

Fantom API method that returns traces for all the transactions within a specific block. Developers can use the trace_block method to gain insight into the behavior of smart contracts within a block, analyze gas usage, and optimize their contracts accordingly. This method is only available on an Erigon instance.


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  • quantity or tag β€” the integer of a block encoded as hexadecimal or the string with:

    • latest β€” the most recent block in the blockchain and the current state of the blockchain at the most recent block. A chain reorganization is to be expected.

    • safe β€” the block that received justification from the beacon chain. Although this block could be involved in a chain reorganization, it would necessitate either a coordinated attack by the majority of validators or an instance of severe propagation latency.

    • finalized β€” the block accepted as canonical by more than 2/3 of the validators. A chain reorganization is extremely unlikely, and it would require at least 1/3 of the staked ETH to be burned.

    • earliest β€” the earliest available or genesis block

    • pending β€” the pending state and transactions block. The current state of transactions that have been broadcast to the network but have not yet been included in a block.


      See the default block parameter and How The Merge Impacts Ethereum’s Application Layer.


  • result β€” an object containing the traces of all of the transactions in the block:
    • 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_block code examples

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

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

    async traceBlock(blockId) {
        return this.requestManager.send({
            method: 'trace_block',
            params: [blockId],

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

async function traceBlock(block) {
    const result = await web3.erigon.traceBlock(block);

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

const traceBlock = async (block) => {
  const traces = await provider.send("trace_block", [block]);

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

block = "latest"

traces = web3.provider.make_request('trace_block', [block])

Use case

A practical use case for the trace_block method on Ethereum can be to analyze the most recent block on the network. For example, developers can gain valuable insights into the block's behavior by examining the amount of gas supplied by all the transactions and the actual amount of gas utilized. This can be the first step to developing a chain explorer.

Try the trace_block RPC method yourself