ToolVet
77trust / 100

Evm Tx Inspect

by Preflight in Onchain & crypto

x402 APIPassing, checked 1 h ago

Call before signing an Ethereum or Base transaction or calldata. Decodes raw transaction bytes or contract calldata against standard interfaces (ERC-20, ERC-721, ERC-1155, WETH, EIP-2612 Permit and Permit2) in memory. Returns the decoded method signature, typed parameters, value in wei and standard specification links. Mechanical byte decoding only: never simulates state or advises whether to sign.

POST https://preflight402.com/v1/evm/tx-inspect

Last 30 days

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Status and outage history · Atom feed

Uptime
100%
Response time
599 ms typical, 897 ms slowest 5%
Last check
1 h ago
Next check
any minute now

How to call it

POST https://preflight402.com/v1/evm/tx-inspect

Each call costs $0.1 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.

POST https://preflight402.com/v1/evm/tx-inspect
content-type: application/json

{
  "calldata": "0xa9059cbb000000000000000000000000222222222222222222222222222222222222222200000000000000000000000000000000000000000000000000000000000f4240",
  "network": "base",
  "to": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913"
}

Parameters

ParameterTypeRequiredDescription
calldatastringNo
networkstringYes One of: ethereum, base.
raw_txstringNo
tostringNo

Example response

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

Example response, 29 lines
{
  "arguments": [
    {
      "name": "to",
      "type": "address",
      "value": "0x2222222222222222222222222222222222222222"
    },
    {
      "name": "amount",
      "type": "uint256",
      "value": "1000000"
    }
  ],
  "chain_id": 8453,
  "decode_status": "decoded",
  "input_kind": "calldata",
  "method_signatures": [
    "transfer(address to, uint256 amount)"
  ],
  "network": "base",
  "official_url": "https://eips.ethereum.org/EIPS/eip-20",
  "selector": "0xa9059cbb",
  "standard_urls": [
    "https://eips.ethereum.org/EIPS/eip-20"
  ],
  "to": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
  "transaction_type": null,
  "value_wei": null
}

Call it from code

The curl command shows the payment challenge. The JavaScript and Python versions pay and call, and never pay more than $0.1.

curl: see the payment challenge
# bash or zsh: see the payment challenge. Nothing is charged.
curl -sS -g -i -X POST 'https://preflight402.com/v1/evm/tx-inspect' \
  -H 'content-type: application/json' \
  --data-raw '{"calldata":"0xa9059cbb000000000000000000000000222222222222222222222222222222222222222200000000000000000000000000000000000000000000000000000000000f4240","network":"base","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 - -X POST 'https://preflight402.com/v1/evm/tx-inspect' \
  -H 'content-type: application/json' \
  --data-raw '{"calldata":"0xa9059cbb000000000000000000000000222222222222222222222222222222222222222200000000000000000000000000000000000000000000000000000000000f4240","network":"base","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 $0.1 per call.
const client = new x402Client().setSpendControls({ maxAmountPerPayment: "$0.1" });
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 $0.1 per payment. GET https://toolvet.app/api/v1/check?url=https%3A%2F%2Fpreflight402.com%2Fv1%2Fevm%2Ftx-inspect&method=POST
const res = await pay("https://preflight402.com/v1/evm/tx-inspect", {
  method: "POST",
  headers: { "content-type": "application/json" },
  body: JSON.stringify({
    "calldata": "0xa9059cbb000000000000000000000000222222222222222222222222222222222222222200000000000000000000000000000000000000000000000000000000000f4240",
    "network": "base",
    "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 $0.1 per call.
client = x402ClientSync().set_spend_controls({"max_amount_per_payment": "$0.1"})
register_exact_evm_client(client, EthAccountSigner(Account.from_key(os.environ["EVM_PRIVATE_KEY"])))

with x402_requests(client) as session:
    res = session.post(
        "https://preflight402.com/v1/evm/tx-inspect",
        json={
            "calldata": "0xa9059cbb000000000000000000000000222222222222222222222222222222222222222200000000000000000000000000000000000000000000000000000000000f4240",
            "network": "base",
            "to": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
        },
    )
    print(res.status_code, res.text)

Security scan

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