trace_call | Tempo

Tempo API method that traces a call without creating a transaction. This provides detailed execution traces using the Parity/OpenEthereum trace format.

Parameters

• callObject — the call object:
  • from — (optional) sender address
  • to — recipient address
  • gas — (optional) gas limit
  • gasPrice — (optional) gas price
  • value — (optional) value to send
  • data — (optional) call data
• traceTypes — array of trace types to include:
  • trace — basic execution trace
  • vmTrace — full VM execution trace
  • stateDiff — state changes
• blockParameter — the block number (hex) or tag (latest, earliest, pending)

Response

• result — the trace result object:
  • output — return data from the call
  • trace — array of trace objects (if requested)
  • vmTrace — VM execution trace (if requested)
  • stateDiff — state differences (if requested)

trace_call code examples

The following example traces a balanceOf call on the pathUSD token:

ethers.js

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

// pathUSD token address
const PATHUSD = "0x20c0000000000000000000000000000000000000";
const TARGET_ADDRESS = "0x9729187D9E8Bbefa8295F39f5634cA454dd9d294";

// Encode balanceOf(address)
const iface = new ethers.Interface(["function balanceOf(address) view returns (uint256)"]);
const data = iface.encodeFunctionData("balanceOf", [TARGET_ADDRESS]);

const traceCall = async () => {
    const result = await provider.send("trace_call", [
      {
        to: PATHUSD,
        data: data
      },
      ["trace", "stateDiff"],
      "latest"
    ]);

    console.log("Output:", result.output);
    console.log("Traces:", result.trace.length);

    if (result.stateDiff) {
      console.log("State changes:", Object.keys(result.stateDiff).length, "addresses affected");
    }
  };

traceCall();