ToolVet
77trust / 100

Simulate Tx

by Transaction Simulation in Onchain & crypto

x402 APIPassing, checked 3 h ago

Simulate an UNSIGNED transaction against live Base state before an agent signs: will it SUCCEED or revert (with the contract's own reason), the gas estimate and ETH cost, and — decoded from the calldata — whether it grants an approval, and whether that approval is UNLIMITED (approve/permit) or a setApprovalForAll, the classic drain vectors. Pass from, to, and optionally data (calldata) + value. The pre-execution check the agent-safety playbook says to run and block on. Not financial advice.

GET
https://402.com.tr/api/x402/simulate-tx
Price
$0.03
per call in USDC
Uptime
100%
last 30 days
Response time
451 ms
546 ms slowest 5%
Last check
Passed
3 h ago, next any minute now

Run a free test callHow to call it

Reliability

All checks passedSome failedAll failedNot checked

Status and outage history · Atom feed

How to call it

GET https://402.com.tr/api/x402/simulate-tx

Each call costs $0.03 in USDC on Base, paid with the request over x402.

Run a free test callOne unpaid request, the way an agent sends it. You see the payment challenge it gets back. Nothing is charged.

Example request

From the listing.

GET https://402.com.tr/api/x402/simulate-tx?data=0x095ea7b3000000000000000000000000cf77a3ba9a5ca399b7c97c74d54e5b1beb874e430000000000000000000000000000000000000000000000000000000000000000&from=0x973a31858f4d2125f48c880542da11a2796f12d6&to=0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913&value=0.1

Parameters

ParameterTypeRequiredDescription
datastringNoCalldata (hex, optional)
fromstringYesSender address
tostringYesTo (recipient/contract)
valuestringNoETH value (optional)

Example response

The provider's example. We can't check it without paying.

{
  "from": "0x973A31858f4D2125f48C880542DA11a2796f12D6",
  "gasCostEth": null,
  "gasEstimate": null,
  "method": "approve",
  "riskLevel": "review",
  "to": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
  "valueEth": "0.1",
  "willSucceed": false
}

Call it from code

The curl command shows the payment challenge. The JavaScript and Python versions pay and call, and never pay more than $0.03.

curl: see the payment challenge
# bash or zsh: see the payment challenge. Nothing is charged.
curl -sS -g -i 'https://402.com.tr/api/x402/simulate-tx?data=0x095ea7b3000000000000000000000000cf77a3ba9a5ca399b7c97c74d54e5b1beb874e430000000000000000000000000000000000000000000000000000000000000000&from=0x973a31858f4d2125f48c880542da11a2796f12d6&to=0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913&value=0.1'

# x402 v2 sends the challenge base64-encoded in the PAYMENT-REQUIRED header (v1 sends it in the body).
# To read the header:
curl -sS -g -o /dev/null -D - 'https://402.com.tr/api/x402/simulate-tx?data=0x095ea7b3000000000000000000000000cf77a3ba9a5ca399b7c97c74d54e5b1beb874e430000000000000000000000000000000000000000000000000000000000000000&from=0x973a31858f4d2125f48c880542da11a2796f12d6&to=0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913&value=0.1' \
  | grep -i '^payment-required:' | cut -d' ' -f2 | tr -d '\r' | base64 --decode
JavaScript: pay and call
// npm i @x402/fetch @x402/evm viem
import { wrapFetchWithPayment, x402Client } from "@x402/fetch";
import { registerExactEvmScheme } from "@x402/evm/exact/client";
import { privateKeyToAccount } from "viem/accounts";

// Pays at most $0.03 per call.
const client = new x402Client().setSpendControls({ maxAmountPerPayment: "$0.03" });
registerExactEvmScheme(client, { signer: privateKeyToAccount(process.env.EVM_PRIVATE_KEY) });
const pay = wrapFetchWithPayment(fetch, client);

// Not sure it's safe to pay? ToolVet checks it first for $0.005. Pay for that from a separate
// client: this one is capped at $0.03 per payment. GET https://toolvet.app/api/v1/check?url=https%3A%2F%2F402.com.tr%2Fapi%2Fx402%2Fsimulate-tx
const res = await pay("https://402.com.tr/api/x402/simulate-tx?data=0x095ea7b3000000000000000000000000cf77a3ba9a5ca399b7c97c74d54e5b1beb874e430000000000000000000000000000000000000000000000000000000000000000&from=0x973a31858f4d2125f48c880542da11a2796f12d6&to=0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913&value=0.1");
console.log(res.status, await res.text());
Python: pay and call
# pip install "x402[requests,evm]"
import os
from eth_account import Account
from x402 import x402ClientSync
from x402.http.clients import x402_requests
from x402.mechanisms.evm import EthAccountSigner
from x402.mechanisms.evm.exact.register import register_exact_evm_client

# Pays at most $0.03 per call.
client = x402ClientSync().set_spend_controls({"max_amount_per_payment": "$0.03"})
register_exact_evm_client(client, EthAccountSigner(Account.from_key(os.environ["EVM_PRIVATE_KEY"])))

with x402_requests(client) as session:
    res = session.get("https://402.com.tr/api/x402/simulate-tx?data=0x095ea7b3000000000000000000000000cf77a3ba9a5ca399b7c97c74d54e5b1beb874e430000000000000000000000000000000000000000000000000000000000000000&from=0x973a31858f4d2125f48c880542da11a2796f12d6&to=0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913&value=0.1")
    print(res.status_code, res.text)

Security scan

No findings

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Recent checks

WhenResultHTTPTimePrice
3 h agoPassed402451 ms$0.03
7 h agoPassed402445 ms$0.03
11 h agoPassed402442 ms$0.03
15 h agoPassed402406 ms$0.03
19 h agoPassed402420 ms$0.03
Show 10 older checks
23 h agoPassed402526 ms$0.03
26 h agoPassed402363 ms$0.03
31 h agoPassed402440 ms$0.03
34 h agoPassed402371 ms$0.03
38 h agoPassed402397 ms$0.03
41 h agoPassed402641 ms$0.03
45 h agoPassed402546 ms$0.03
2 days agoPassed402508 ms$0.03
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2 days agoPassed402500 ms$0.03