debug_traceCall

POSThttps://api.triport.io/v1/eth

Executes an `eth_call` against the state of a chosen block and returns the full EVM execution trace, without broadcasting a transaction.

Ethereumeth_debugpro — 5 RPS · business — 15 RPS

debug_traceCall simulates a contract call exactly as eth_call would, but instead of returning only the call's return data it returns a structured EVM execution trace. The call is evaluated against the state at the supplied block — nothing is broadcast and no state is persisted. Use it to debug why a call reverts, to inspect internal call hierarchies and gas accounting, or to preview the effect of a transaction before sending it.

The method is part of the debug namespace and is available on the pro and business tiers. Because producing a trace is more expensive than a plain eth_call, the per-second limits are lower than for standard eth_* read methods.

By default the method uses the built-in struct/opcode logger, which emits one entry per executed opcode. For higher-level output pass a named tracer such as callTracer (call hierarchy) or prestateTracer (pre-execution state) in the options object.

Parameters

The params array is positional: [callObject, blockParameter, options?].

callObjectobjectrequired

The transaction-call object to simulate. See fields below.

blockParameterstringrequired

Block to evaluate the call against — a hex-encoded block number (e.g. 0x10d4f) or a tag: latest, earliest, pending, safe, finalized.

optionsobjectoptional

Tracer configuration object. See fields below.

callObject fieldsobject

tostringrequired

Address of the contract being called.

fromstringoptional

Sender address the call executes as. Defaults to the zero address.

datastringoptional

Hex-encoded ABI call data (method selector + arguments).

valuestringoptional

Hex-encoded wei value to send with the call.

gasstringoptional

Hex-encoded gas limit for the call.

gasPricestringoptional

Hex-encoded gas price in wei.

options fieldsobject

tracerstring

Named tracer: callTracer, prestateTracer, 4byteTracer, or a custom JS tracer.

tracerConfigobject

Tracer-specific options, e.g. { "onlyTopCall": true } for callTracer.

timeoutstring

Max trace duration, Go duration string (e.g. 10s).

Response

Response fields

The shape of result depends on the selected tracer. The example above shows the callTracer output (a single top-level call frame).

Field	Type	Description
`result`	object	Trace output for the simulated call.
`result.type`	string	Call type: `CALL`, `DELEGATECALL`, `STATICCALL`, `CREATE`, etc.
`result.from`	string	Sender address of the call frame.
`result.to`	string	Recipient address of the call frame.
`result.value`	string	Wei transferred with the call frame, hex-encoded.
`result.gas`	string	Gas supplied to the call frame, hex-encoded.
`result.gasUsed`	string	Gas consumed by the call frame, hex-encoded.
`result.input`	string	Call data passed into the frame.
`result.output`	string	Return data from the frame.
`result.calls`	array	Nested child call frames (present with `callTracer`).
`result.error`	string	Present only when the frame reverted; holds the revert reason.

With the default struct logger, result instead contains gas, failed, returnValue, and a structLogs array with one entry per executed opcode.

Errors

Code	Meaning	When it happens
-32602	Invalid params	Malformed call object, bad block parameter, unknown tracer name, or bad `tracerConfig`.
-32002	Tier insufficient	API key is on the free tier; `debug` methods require pro or business.
-32003	Rate limited	Per-second limit for your tier exceeded; back off and retry.
-32000	Server error	Block not found, the call reverted at the EVM level, or the trace exceeded the configured `timeout`.

See errors.md for the full error envelope.

Examples

JavaScript (fetch)

JavaScript

const res = await fetch("https://api.triport.io/v1/eth", {
  method: "POST",
  headers: {
    "Authorization": `Bearer ${process.env.TRIPORT_API_KEY}`,
    "Content-Type": "application/json",
  },
  body: JSON.stringify({
    jsonrpc: "2.0",
    id: 1,
    method: "debug_traceCall",
    params: [
      {
        from: "0x8894e0a0c962cb723c1976a4421c95949be2d4e3",
        to: "0xb5a5f22694352c15b00323844ad545abb2b11028",
        data: "0xa9059cbb0000000000000000000000005b38da6a701c568545dcfcb03fcb875f56beddc40000000000000000000000000000000000000000000000000000000000000064",
      },
      "latest",
      { tracer: "callTracer" },
    ],
  }),
});
const { result } = await res.json();
console.log(result);

TypeScript SDK (`@triport/sdk`)

TypeScript

import { Triport } from "@triport/sdk";


const triport = new Triport({ apiKey: process.env.TRIPORT_API_KEY! });


const trace = await triport.eth.debugTraceCall(
  {
    from: "0x8894e0a0c962cb723c1976a4421c95949be2d4e3",
    to: "0xb5a5f22694352c15b00323844ad545abb2b11028",
    data: "0xa9059cbb0000000000000000000000005b38da6a701c568545dcfcb03fcb875f56beddc40000000000000000000000000000000000000000000000000000000000000064",
  },
  "latest",
  { tracer: "callTracer" },
);
console.log(trace);

Python (`triport-sdk`)

Python

from triport import Triport


triport = Triport(api_key=os.environ["TRIPORT_API_KEY"])


trace = triport.eth.debug_trace_call(
    {
        "from": "0x8894e0a0c962cb723c1976a4421c95949be2d4e3",
        "to": "0xb5a5f22694352c15b00323844ad545abb2b11028",
        "data": "0xa9059cbb0000000000000000000000005b38da6a701c568545dcfcb03fcb875f56beddc40000000000000000000000000000000000000000000000000000000000000064",
    },
    "latest",
    tracer="callTracer",
)
print(trace)

Notes

Unlike eth_call, this method does not return only the call's return data — it returns a full trace. If you only need the return value, use eth_call; it is available at the free tier and far cheaper.
The struct logger (default tracer) can produce very large responses for complex calls. Prefer callTracer or prestateTracer unless you need opcode-level detail.
To trace a call that has already been mined, use debug_traceTransaction. To trace every transaction in a block, use debug_traceBlockByNumber or debug_traceBlockByHash.
Tracer selection, tracerConfig, and timeout behave identically across all debug_trace* methods.
A call that reverts is still a successful JSON-RPC response: the revert is reported inside the trace (result.error with callTracer, or failed: true with the struct logger), not as a top-level error.

Request

cURLJavaScriptPython

curl https://api.triport.io/v1/eth \
  -H "Authorization: Bearer $TRIPORT_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "jsonrpc": "2.0",
    "id": 1,
    "method": "debug_traceCall",
    "params": [
      {
        "from": "0x8894e0a0c962cb723c1976a4421c95949be2d4e3",
        "to": "0xb5a5f22694352c15b00323844ad545abb2b11028",
        "data": "0xa9059cbb0000000000000000000000005b38da6a701c568545dcfcb03fcb875f56beddc40000000000000000000000000000000000000000000000000000000000000064"
      },
      "latest",
      { "tracer": "callTracer" }
    ]
  }'

const res = await fetch("https://api.triport.io/v1/eth", {
  method: "POST",
  headers: {
    "Authorization": "Bearer $TRIPORT_API_KEY",
    "Content-Type": "application/json",
  },
  body: JSON.stringify({
    "jsonrpc": "2.0",
    "id": 1,
    "method": "debug_traceCall",
    "params": [
      {
        "from": "0x8894e0a0c962cb723c1976a4421c95949be2d4e3",
        "to": "0xb5a5f22694352c15b00323844ad545abb2b11028",
        "data": "0xa9059cbb0000000000000000000000005b38da6a701c568545dcfcb03fcb875f56beddc40000000000000000000000000000000000000000000000000000000000000064"
      },
      "latest",
      {
        "tracer": "callTracer"
      }
    ]
  }),
});
const data = await res.json();
console.log(data);

import requests


resp = requests.post(
    "https://api.triport.io/v1/eth",
    headers={
        "Authorization": "Bearer $TRIPORT_API_KEY",
        "Content-Type": "application/json",
    },
    json={
        "jsonrpc": "2.0",
        "id": 1,
        "method": "debug_traceCall",
        "params": [
            {
                "from": "0x8894e0a0c962cb723c1976a4421c95949be2d4e3",
                "to": "0xb5a5f22694352c15b00323844ad545abb2b11028",
                "data": "0xa9059cbb0000000000000000000000005b38da6a701c568545dcfcb03fcb875f56beddc40000000000000000000000000000000000000000000000000000000000000064",
            },
            "latest",
            {
                "tracer": "callTracer",
            },
        ],
    },
)
data = resp.json()
print(data)

Response 200

JSON

{
  "jsonrpc": "2.0",
  "id": 1,
  "result": {
    "type": "CALL",
    "from": "0x8894e0a0c962cb723c1976a4421c95949be2d4e3",
    "to": "0xb5a5f22694352c15b00323844ad545abb2b11028",
    "value": "0x0",
    "gas": "0x13880",
    "gasUsed": "0x6c1c",
    "input": "0xa9059cbb0000000000000000000000005b38da6a701c568545dcfcb03fcb875f56beddc40000000000000000000000000000000000000000000000000000000000000064",
    "output": "0x0000000000000000000000000000000000000000000000000000000000000001",
    "calls": []
  }
}