ToolVet
80trust / 100

Simulate

by TxSim Decoder in Onchain & crypto

x402 APIPassing, checked 3 h ago

Simulate an EVM transaction before signing. Decodes the calldata into a named function with arguments and security risk flags, AND runs a keyless static eth_call preview to tell you whether the transaction would succeed or revert (with the decoded revert reason). Use it to catch a failing or malicious transaction before you broadcast it. Read-only, no keys, no node infra. Asset-level change tracing is v2.

GET
https://simulate.cyberwarex.com/simulate
Price
$0.005
per call in USDC
Uptime
100%
last 30 days
Response time
161 ms
292 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 · Watch with other listings

How to call it

GET https://simulate.cyberwarex.com/simulate

Each call costs $0.005 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://simulate.cyberwarex.com/simulate?chain=base&data=0xa9059cbb000000000000000000000000d8da6bf26964af9d7eed9e03e53415d37aa960450000000000000000000000000000000000000000000000000000000005f5e100&from=0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045&to=0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913

Parameters

ParameterTypeRequiredDescription
chainstringNoEVM chain to simulate on. One of: base, ethereum, arbitrum, optimism, polygon, bsc. Default: "base".
datastringNoTransaction calldata (hex).
fromstringNoSender address for the eth_call preview.
tostringYesTarget contract or account address.
valuestringNoNative value in wei (optional, decimal or 0x hex).

Example response

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

{
  "asset_changes": null,
  "chain": "base",
  "decoded": {
    "args": {
      "amount": "100000000",
      "to": "0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045"
    },
    "function": "transfer",
    "signature": "transfer(address,uint256)"
  },
  "disclaimer": "Static decode + keyless eth_call preview only. This is not financial advice and not a guarantee: a call that would succeed now can still revert at broadcast time (state changes, slippage, MEV). Always verify before signing.",
  "note": "asset-level change tracing requires a tracing RPC key (v2)",
  "revert_reason": null,
  "risk": {
    "flags": [],
    "level": "none"
  },
  "to": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
  "would_succeed": true
}

Call it from code

The curl command shows the payment challenge. The JavaScript and Python versions pay and call, and never pay more than $0.005.

curl: see the payment challenge
# bash or zsh: see the payment challenge. Nothing is charged.
curl -sS -g -i 'https://simulate.cyberwarex.com/simulate?chain=base&data=0xa9059cbb000000000000000000000000d8da6bf26964af9d7eed9e03e53415d37aa960450000000000000000000000000000000000000000000000000000000005f5e100&from=0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045&to=0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913'

# 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://simulate.cyberwarex.com/simulate?chain=base&data=0xa9059cbb000000000000000000000000d8da6bf26964af9d7eed9e03e53415d37aa960450000000000000000000000000000000000000000000000000000000005f5e100&from=0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045&to=0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913' \
  | 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 $0.005 per call.
const client = new x402Client().setSpendControls({ maxAmountPerPayment: "$0.005" });
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 $0.005 per payment. GET https://toolvet.app/api/v1/check?url=https%3A%2F%2Fsimulate.cyberwarex.com%2Fsimulate
const res = await pay("https://simulate.cyberwarex.com/simulate?chain=base&data=0xa9059cbb000000000000000000000000d8da6bf26964af9d7eed9e03e53415d37aa960450000000000000000000000000000000000000000000000000000000005f5e100&from=0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045&to=0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913");
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 $0.005 per call.
client = x402ClientSync().set_spend_controls({"max_amount_per_payment": "$0.005"})
register_exact_evm_client(client, EthAccountSigner(Account.from_key(os.environ["EVM_PRIVATE_KEY"])))

with x402_requests(client) as session:
    res = session.get("https://simulate.cyberwarex.com/simulate?chain=base&data=0xa9059cbb000000000000000000000000d8da6bf26964af9d7eed9e03e53415d37aa960450000000000000000000000000000000000000000000000000000000005f5e100&from=0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045&to=0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913")
    print(res.status_code, res.text)

Security scan

No findings

We scan names, descriptions and tool definitions for hidden instructions and other prompt-injection patterns.

Recent checks

WhenResultHTTPTimePrice
3 h agoPassed402292 ms$0.005
13 h agoPassed402176 ms$0.005
17 h agoPassed402111 ms$0.005
21 h agoPassed402161 ms$0.005
25 h agoPassed402126 ms$0.005
Show 1 older checks
29 h agoPassed402163 ms$0.005