ToolVet
81trust / 100

Check

by CORS Header Checker in Search & web

x402 APIPassing, checked 4 h ago

Sends a real request to any URL you provide, attaches an Origin header, and reads back all six standard cross-origin permission headers the server returns. Tells you whether cross-origin requests are enabled at all, whether your specific origin is permitted, and shows every permission value exactly as the server sent it. Useful for finding why a browser is blocking a request, confirming a new deployment is configured correctly, or auditing whether a public API allows credentialed calls.

POST
https://cors-header-checker.underscoredone.com/check
Price
$0.01
per call in USDC
Uptime
100%
last 30 days
Response time
286 ms
447 ms slowest 5%
Last check
Passed
4 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://cors-header-checker.underscoredone.com/check

Each call costs $0.01 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://cors-header-checker.underscoredone.com/check
content-type: application/json

{
  "origin": "https://myapp.com",
  "url": "https://api.github.com"
}

Parameters

ParameterTypeRequiredDescription
originstringNoThe website address you want to test cross-origin access from, for example https://myapp.com. Defaults to https://example.com if you leave it out.
urlstringYesThe full web address of the endpoint you want to check — must start with http:// or https://.

Example response

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

{
  "api_version": "1.0.0",
  "cors_enabled": true,
  "error": "",
  "headers": {
    "access-control-allow-credentials": null,
    "access-control-allow-headers": null,
    "access-control-allow-methods": null,
    "access-control-allow-origin": "https://github.com",
    "access-control-expose-headers": "ETag, Link, Location, Retry-After, X-GitHub-OTP, X-RateLimit-Limit, X-RateLimit-Remaining, X-RateLimit-Used, X-RateLimit-Resource, X-RateLimit-Reset, X-OAuth-Scopes, X-Accepted-OAuth-Scopes, X-Poll-Interval, X-GitHub-Media-Type, X-GitHub-SSO, X-GitHub-Request-Id, Deprecation, Sunset",
    "access-control-max-age": null
  },
  "origin_allowed": false,
  "origin_tested": "https://myapp.com",
  "status": 200,
  "url": "https://api.github.com"
}

Call it from code

The curl command shows the payment challenge. The JavaScript and Python versions pay and call, and never pay more than $0.01.

curl: see the payment challenge
# bash or zsh: see the payment challenge. Nothing is charged.
curl -sS -g -i -X POST 'https://cors-header-checker.underscoredone.com/check' \
  -H 'content-type: application/json' \
  --data-raw '{"origin":"https://myapp.com","url":"https://api.github.com"}'

# 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://cors-header-checker.underscoredone.com/check' \
  -H 'content-type: application/json' \
  --data-raw '{"origin":"https://myapp.com","url":"https://api.github.com"}' \
  | 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 $0.01 per call.
const client = new x402Client().setSpendControls({ maxAmountPerPayment: "$0.01" });
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 $0.01 per payment. GET https://toolvet.app/api/v1/check?url=https%3A%2F%2Fcors-header-checker.underscoredone.com%2Fcheck&method=POST
const res = await pay("https://cors-header-checker.underscoredone.com/check", {
  method: "POST",
  headers: { "content-type": "application/json" },
  body: JSON.stringify({
    "origin": "https://myapp.com",
    "url": "https://api.github.com"
  }),
});
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 $0.01 per call.
client = x402ClientSync().set_spend_controls({"max_amount_per_payment": "$0.01"})
register_exact_evm_client(client, EthAccountSigner(Account.from_key(os.environ["EVM_PRIVATE_KEY"])))

with x402_requests(client) as session:
    res = session.post(
        "https://cors-header-checker.underscoredone.com/check",
        json={
            "origin": "https://myapp.com",
            "url": "https://api.github.com",
        },
    )
    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
4 h agoPassed402308 ms$0.01
8 h agoPassed402286 ms$0.01
13 h agoPassed402322 ms$0.01
17 h agoPassed402352 ms$0.01
21 h agoPassed402340 ms$0.01
Show 10 older checks
25 h agoPassed402349 ms$0.01
29 h agoPassed402317 ms$0.01
34 h agoPassed402232 ms$0.01
38 h agoPassed402227 ms$0.01
42 h agoPassed402447 ms$0.01
46 h agoPassed402258 ms$0.01
2 days agoPassed402746 ms$0.01
2 days agoPassed402238 ms$0.01
2 days agoPassed402284 ms$0.01
3 days agoPassed402240 ms$0.01