ToolVet
77trust / 100

X402 Check

by AIMarket in Onchain & crypto

x402 APIPassing, checked 3 h ago

Debug an x402 payment before you submit it — why does USDC answer invalid signature? Verifies the EIP-3009 transferWithAuthorization (EIP-712 signer, v, low s, validity window) and the seller's terms (payTo, amount, asset, network, bound nonce), and names the domain a failing signature was really made for, e.g. Base Sepolia's 'USDC' used for Base mainnet's 'USD Coin', the commonest reason an x402 payment reverts. Offline, deterministic, signed answer.

POST
https://modelmarket.dev/x402/x402-check
Price
$0.003
per call in USDC
Uptime
100%
last 30 days
Response time
437 ms
636 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

POST https://modelmarket.dev/x402/x402-check

Each call costs $0.003 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://modelmarket.dev/x402/x402-check
content-type: application/json

{
  "authorization": {
    "from": "0x9993C13EBBC4B98441E38585eA47fe17625f04f3",
    "nonce": "0x52293a780cf1f48ea8a555187c01b15124c41cfef04114b44f3e5463ce8b30eb",
    "to": "0x1218ff36C5d2e3B6A565CdB1A8B1AcCFc606Ad0a",
    "validAfter": "0",
    "validBefore": "1893456000",
    "value": "3000"
  },
  "network": "base",
  "signature": "0xe0949d03ce604032721cf706d05897c9b5b34dbc0d3f4a76848724c1e20473330238f0dde1ea3cccffce4c1d1f5a6dfbfb0012ec42a9fd2165bc9723b14b56381b"
}

Parameters

ParameterTypeRequiredDescription
authorizationobjectNofrom, to, value, validAfter, validBefore, nonce
networkstringNobase, base-sepolia, … or eip155:<chain id>
nowintegerNounix seconds, to check the validity window
requirementsobjectNothe 402's accepts entry (payTo, amount, asset, network)
signaturestringNo65-byte hex signature
x_paymentstringNothe X-PAYMENT header (base64) — or authorization + signature + network

Example response

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

{
  "capability_id": "x402.authorization.check@v1",
  "receipt": {},
  "result": {},
  "service": "x402-check",
  "status": "ok"
}

Call it from code

The curl command shows the payment challenge. The JavaScript and Python versions pay and call, and never pay more than $0.003.

curl: see the payment challenge
# bash or zsh: see the payment challenge. Nothing is charged.
curl -sS -g -i -X POST 'https://modelmarket.dev/x402/x402-check' \
  -H 'content-type: application/json' \
  --data-raw '{"authorization":{"from":"0x9993C13EBBC4B98441E38585eA47fe17625f04f3","nonce":"0x52293a780cf1f48ea8a555187c01b15124c41cfef04114b44f3e5463ce8b30eb","to":"0x1218ff36C5d2e3B6A565CdB1A8B1AcCFc606Ad0a","validAfter":"0","validBefore":"1893456000","value":"3000"},"network":"base","signature":"0xe0949d03ce604032721cf706d05897c9b5b34dbc0d3f4a76848724c1e20473330238f0dde1ea3cccffce4c1d1f5a6dfbfb0012ec42a9fd2165bc9723b14b56381b"}'

# 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://modelmarket.dev/x402/x402-check' \
  -H 'content-type: application/json' \
  --data-raw '{"authorization":{"from":"0x9993C13EBBC4B98441E38585eA47fe17625f04f3","nonce":"0x52293a780cf1f48ea8a555187c01b15124c41cfef04114b44f3e5463ce8b30eb","to":"0x1218ff36C5d2e3B6A565CdB1A8B1AcCFc606Ad0a","validAfter":"0","validBefore":"1893456000","value":"3000"},"network":"base","signature":"0xe0949d03ce604032721cf706d05897c9b5b34dbc0d3f4a76848724c1e20473330238f0dde1ea3cccffce4c1d1f5a6dfbfb0012ec42a9fd2165bc9723b14b56381b"}' \
  | 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 $0.003 per call.
const client = new x402Client().setSpendControls({ maxAmountPerPayment: "$0.003" });
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 $0.003 per payment. GET https://toolvet.app/api/v1/check?url=https%3A%2F%2Fmodelmarket.dev%2Fx402%2Fx402-check&method=POST
const res = await pay("https://modelmarket.dev/x402/x402-check", {
  method: "POST",
  headers: { "content-type": "application/json" },
  body: JSON.stringify({
    "authorization": {
      "from": "0x9993C13EBBC4B98441E38585eA47fe17625f04f3",
      "nonce": "0x52293a780cf1f48ea8a555187c01b15124c41cfef04114b44f3e5463ce8b30eb",
      "to": "0x1218ff36C5d2e3B6A565CdB1A8B1AcCFc606Ad0a",
      "validAfter": "0",
      "validBefore": "1893456000",
      "value": "3000"
    },
    "network": "base",
    "signature": "0xe0949d03ce604032721cf706d05897c9b5b34dbc0d3f4a76848724c1e20473330238f0dde1ea3cccffce4c1d1f5a6dfbfb0012ec42a9fd2165bc9723b14b56381b"
  }),
});
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 $0.003 per call.
client = x402ClientSync().set_spend_controls({"max_amount_per_payment": "$0.003"})
register_exact_evm_client(client, EthAccountSigner(Account.from_key(os.environ["EVM_PRIVATE_KEY"])))

with x402_requests(client) as session:
    res = session.post(
        "https://modelmarket.dev/x402/x402-check",
        json={
            "authorization": {
                "from": "0x9993C13EBBC4B98441E38585eA47fe17625f04f3",
                "nonce": "0x52293a780cf1f48ea8a555187c01b15124c41cfef04114b44f3e5463ce8b30eb",
                "to": "0x1218ff36C5d2e3B6A565CdB1A8B1AcCFc606Ad0a",
                "validAfter": "0",
                "validBefore": "1893456000",
                "value": "3000",
            },
            "network": "base",
            "signature": "0xe0949d03ce604032721cf706d05897c9b5b34dbc0d3f4a76848724c1e20473330238f0dde1ea3cccffce4c1d1f5a6dfbfb0012ec42a9fd2165bc9723b14b56381b",
        },
    )
    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 agoPassed402428 ms$0.003
8 h agoPassed402466 ms$0.003
13 h agoPassed402551 ms$0.003
18 h agoPassed402432 ms$0.003
22 h agoPassed402530 ms$0.003
Show 10 older checks
27 h agoPassed402390 ms$0.003
31 h agoPassed402396 ms$0.003
36 h agoPassed402428 ms$0.003
40 h agoPassed402392 ms$0.003
44 h agoPassed402456 ms$0.003
2 days agoPassed402354 ms$0.003
2 days agoPassed402589 ms$0.003
2 days agoPassed402435 ms$0.003
3 days agoPassed402452 ms$0.003
3 days agoPassed402424 ms$0.003