An independent test of your x402 endpoint, by the team that checks the ERC-8004 agent economy every day. (x402 is a standard for paying for a web request with a crypto payment. ERC-8004 is the on-chain list where AI agents register.) We make a real paid call, confirm it on Base, and tell you exactly what is broken.
In our weekly paid tests, — of the — agents we paid delivered what they sold. Last run: 2026-10-31.
Paste the URL of a paid route. We send unpaid requests only and show what a buyer would see. Nothing is paid.
Anyone selling over x402: agents registered under ERC-8004 or not, on any framework. If a buyer can reach a paid route of yours, we can test it. We see what a buyer sees, so the report tells you what a buyer would hit when it tries to pay.
The most common problems we have seen are: a payment request written for a different x402 version than the buyer speaks; a login wall in front of the payment request; a payment service that rejects an ordinary USDC payment; and a missing token name and version, which makes buyers guess wrong. The field test we published on October 11 shows each one.
| Check | Free | Full test ($0.50) |
|---|---|---|
| Your URL answers, with a valid TLS certificate and a reasonable response time | Yes | Yes |
| An unpaid request gets HTTP 402 with a well-formed payment request (version, network, amount, payTo, timeout, token name and version) | Yes | Yes |
| Header and body of the payment request agree; the payment service named in it is reachable | Yes | Yes |
| Discovery files (pricing, OpenAPI, well-known) are present and match the payment request | Yes | Yes |
| A real payment of your listed price, up to $0.10, goes through | No | Yes |
| The payment is confirmed on Base | No | Yes |
| Your endpoint returns a useful answer after it is paid | No | Yes |
| A shareable report and one free re-run within 7 days | No | Yes |
Free checks are limited per visitor and per host each hour. The full test is limited per endpoint each day.
Sample from a real test on November 1, 2026. The seller's name, host and wallet are removed.
Overall: pass. Independent test on 2026-11-01: 22 passed, 0 warnings, 0 failed checks.
This is an independent test on the date shown. It is a snapshot of your endpoint that day, not a rating or a promise about tomorrow.
$0.50 in USDC on Base, paid with x402. Use the API from your own code, or the MCP tool from an agent. The first call returns an x402 payment request; a payment-aware client signs it and retries.
curl -i -X POST https://api.onchainagentintel.io/v1/seller-check \
-H 'Content-Type: application/json' \
-d '{"url":"https://example.com/v1/your-route","method":"GET"}'
# HTTP/1.1 402 Payment Required, with a PAYMENT-REQUIRED header (x402 v2, $0.50 USDC on Base)import { x402Client, wrapFetchWithPayment } from "@x402/fetch";
import { registerExactEvmScheme } from "@x402/evm/exact/client";
import { privateKeyToAccount } from "viem/accounts";
const client = new x402Client();
registerExactEvmScheme(client, { signer: privateKeyToAccount(process.env.PAYER_KEY) });
const payFetch = wrapFetchWithPayment(fetch, client);
const res = await payFetch("https://api.onchainagentintel.io/v1/seller-check", {
method: "POST",
headers: { "Content-Type": "application/json" },
body: JSON.stringify({ url: "https://example.com/v1/your-route", method: "GET" }),
});
console.log(await res.json()); // { report_id, overall, checks, ... }Use a client that speaks x402 version 2; older version 1 clients cannot read our payment request. Agents can also call the seller_check tool on our MCP server at https://api.onchainagentintel.io/mcp. Full details are in the API docs. The report you get back can be opened at https://onchainagentintel.io/seller-check/r/<report_id>.
No. You cannot buy a score. If the endpoint belongs to an agent in the ERC-8004 registry and our paid call is delivered, we record it as a delivered test purchase, the same way we record our own weekly test purchases. A failed call is not recorded against you.
Your listed price, up to $0.10. If your price is higher than $0.10, we run every free check and skip the paid call. We say so in the report.
No. A report is private unless you choose to make it public. Only people who have the report link can open it, and the page asks search engines not to index it.
We do not refund the $0.50 in USDC. If something fails on our side, you get a free re-run, good for 30 days. Every report also includes one free re-run within 7 days, so you can fix the problem and test again.
Yes. Any seller using x402 can test any endpoint, registered or not, on any framework. Registering is optional. ERC-8004 is the on-chain list where AI agents register so buyers can find them.