SiteCheck: pay-per-call tools for AI agents (x402 on Base, Solana and Arc)

Live: https://api.sitecheck-api.workers.dev · listed on x402scan · discovery: /.well-known/x402, /openapi.json

SiteCheck is a small API that AI agents can use without an account or API key: 29 pay-per-call tools in all. Besides its AI and web tools (including a web page to Markdown reader), it sells PDF to text, translation, tech stack detection, sitemap URLs, exchange rates, e-mail, domain and Solana token and wallet data, business and compliance data (EU VAT, IBAN, LEI, US recalls, OSHA/EPA enforcement, UK insolvency notices), prediction-market data and unsigned trade transactions powered by Panta. Every call is paid per request in USDC with the x402 protocol, on Base, Solana or Arc (Circle's L1), whichever the buyer holds USDC on. Call it, get a 402 Payment Required listing the price on each network, sign the payment and get the result. It runs on Cloudflare Workers and Workers AI.

Endpoint	Price	What it does
GET /api/audit?url=	$0.02	Website audit: WCAG 2.2 accessibility issues with fixes and a score (European Accessibility Act), SEO basics, security headers, tech stack
GET /api/contacts?url=	$0.01	Company contact enrichment from a domain: emails, phones, socials, tech
GET /api/hiring?q=&remote=	$0.01	Searches the current Hacker News "Who is hiring?" thread
POST /api/chat	$0.004	Llama 3.3 70B chat completion
POST /api/image	$0.005	FLUX.1 schnell text-to-image
POST /api/transcribe	$0.01	Whisper large-v3-turbo speech-to-text
POST /api/tts	$0.02	Deepgram Aura-2 text-to-speech
POST /api/embed	$0.001	BGE-M3 embeddings (1024-d, multilingual)
GET /api/vat?number=	$0.002	EU VAT number check: format and checksum locally, then the official VIES service (27 EU states + Northern Ireland)
GET /api/iban?iban=	$0.001	IBAN validation with no network call: registry structure and length, mod-97, national check digits, bank/branch/account split; ibans= for up to 50
GET /api/lei?q=	$0.005	GLEIF lookup by LEI or company name: status, registration, parents, children, one-line kycSummary
GET /api/recalls?q=&source=&since=&classification=&limit=	$0.003	US product recalls from openFDA and CPSC in one schema, with a high/medium/low severity
GET /api/violations?company=&state=&since=&minPenalty=&source=&limit=	$0.005	US enforcement cases: OSHA (DOL API, needs a key on the deployment) and EPA ECHO, with official record links
GET /api/uk-insolvency?since=&q=&postcode=&type=&limit=	$0.003	UK company insolvency notices from The Gazette (our nightly cache of the last 8 days), optional Companies House enrichment
GET /api/read?url=&format=&maxChars=&links=	$0.002	One web page as clean Markdown or text for an LLM: main content only, title, description, author, date, language, canonical; robots.txt respected
GET /api/email-check?email=	$0.001	E-mail pre-check without SMTP: syntax, mail DNS, disposable domain, role account, free provider, typo suggestion; emails= for up to 50
GET /api/domain?domain=	$0.002	RDAP (WHOIS successor) and DNS: registered or available, registrar, created/expiry dates, status, DNSSEC, name servers, IPs, MX
GET /api/solana/token?address=	$0.002	Solana token check: price, market cap, liquidity, holders, 24h trading, organic score, top-holder share, on-chain mint/freeze authority and Token-2022 extensions, red flags
GET /api/solana/trending?mode=&interval=&minLiquidityUsd=	$0.003	Trending, new, top-traded or top-organic Solana tokens with the same fields and flags
GET /api/solana/wallet?address=	$0.003	Solana wallet holdings: SOL and every token with symbol, USD price and value, total in USD
GET /api/tech?url=	$0.003	Website technology detection (CMS, e-commerce, analytics, CDN, hosting, chat, payments, e-mail provider) with version, confidence and evidence
POST /api/pdf	$0.003	PDF to text by URL or base64 (up to 15 MB), page by page, with title, author and dates; text PDFs only
GET /api/sitemap?url=&pathPrefix=&since=	$0.002	Every URL in a site's XML sitemaps with lastmod, newest first
GET /api/fx?from=&to=&amount=&date=	$0.001	ECB exchange rates (latest, a past date or a time series) with amount conversion
POST /api/translate	$0.002	Translation with Llama 3.1 8B, up to 6,000 characters, formatting kept

Prediction markets (Panta)

Agents can buy market intelligence and ready-to-sign trade transactions per call, with no account and no API key. An agent researching an event pays a fraction of a cent to find the markets and one cent for a market's odds and a neutral brief. An agent that wants to act pays for an unsigned Panta buy transaction and signs it with its own wallet. Panta runs USDC prediction markets on Solana.

Endpoint	Price	What it does
GET /api/markets?q=&status=&category=&limit=	$0.002	Searches Panta's markets. Compact rows: id, question, YES/NO prices and implied probabilities, volume, close and resolution times, resolution source
GET /api/markets/brief?id=	$0.01	One market: current odds, recent trading activity and a short neutral AI summary of what it asks, what resolves it and what the price implies
POST /api/markets/quote	$0.005	Body { id, side: "yes"|"no", amountUsdc, wallet }. Panta's quote: expected shares, average price, fee, and price impact against the spot price
POST /api/markets/build-buy	$0.01	Same body, plus an optional maxSlippageBps. Returns the unsigned transaction (Solana v0, base64) and Panta's instructions for the agent to sign and broadcast itself, plus the fields for the trade report
POST /api/markets/report	free	After broadcasting, send { signature, orderId, quoteId, id, wallet }. SiteCheck forwards it to Panta, which confirms and attributes the trade

• No custody. SiteCheck never signs, holds keys or custodies funds. build-buy hands back an unsigned transaction whose only signer is the agent's wallet.
• Information only, not financial advice. Every response says so (disclaimer), and the brief never recommends a trade. If the model's text reads like advice, a factual template is returned instead.
• Powered by Panta. Every response carries poweredBy: { text: "Powered by Panta", url: "https://panta.market" }, as Panta's Terms of Use require.
• Pay only for results, as with every tool: if Panta refuses or fails, the call returns an error and nothing is settled. The catalog is cached for 45 seconds and prices for 15 seconds, and responses say how old their data is.
• The tools are on only when the PANTA_API_KEY secret is set. Otherwise they are hidden, and GET /health says why. Endpoints, shapes, attribution and open questions: docs/PANTA.md.

node scripts/demo-markets.mjs --q bitcoin            # search, brief and quote, paid on Solana (~0.017 USDC)
node scripts/demo-markets.mjs --q bitcoin --build    # also builds the unsigned transaction (+0.01); never signs or sends it

Web, documents, e-mail, domain and Solana data

Tool	Source	Notes
/api/read	The page itself, fetched once with the SiteCheckReader User-Agent	robots.txt is respected (a disallowed page answers 403 and is not charged). No JavaScript is run, so pages that only render in the browser come back empty (422, not charged). PDFs and other binary files answer 415. The content belongs to its publisher.
/api/email-check	DNS over HTTPS (Cloudflare, Google) and the disposable-email-domains list (CC0)	No SMTP connection is made: unknown means nothing is wrong with the address or its domain, not that the mailbox exists.
/api/domain	The IANA RDAP bootstrap and each registry's RDAP server; DNS over HTTPS	available means the registry has no record; premium or reserved names can still be unavailable to buy. TLDs without RDAP are inferred from DNS.
/api/solana/token, /api/solana/trending, /api/solana/wallet	Jupiter token, price and holdings APIs, Solana mainnet JSON-RPC (mint account), GeckoTerminal for pools (best effort)	Information only, not financial advice. Nothing is signed or sent. On-chain mint and freeze authority win over the API's audit when both are available.
/api/tech	The site's home page, headers, cookies and DNS (MX, TXT); 231 own fingerprints (MIT, not derived from Wappalyzer)	No JavaScript is run; a site behind a bot challenge returns what its headers and DNS show.
/api/pdf	The PDF's text layer, read with unpdf (PDF.js)	No OCR: a scanned PDF answers 422 and is not charged.
/api/sitemap	The site's robots.txt and XML sitemaps	Indexes are followed up to 25 child sitemaps per call.
/api/fx	European Central Bank reference rates via Frankfurter	Published on working days around 16:00 CET; weekends return the last published day.
/api/translate	Workers AI @cf/meta/llama-3.1-8b-instruct-fast	Machine translation: review important texts.

Business and compliance data

Six tools for an agent that has to check a counterparty before it trades with it. All of them read free official sources (or our own cache of one), need no key from the caller, and follow the same rule as every route here: a call that fails (bad input, upstream down, timeout) returns 4xx/5xx and is not settled, so the buyer is not charged.

Tool	Source	Terms
/api/vat	European Commission VIES REST API	Public service of the Commission. A member state that is down gives HTTP 503 with a viesStatus such as MS_UNAVAILABLE, so an unknown answer is never reported as "invalid". Some states (e.g. DE, ES) confirm validity but do not disclose name and address: those fields are null.
/api/iban	Computed locally from the SWIFT IBAN registry structure (release 101)	No network, no bank-name or BIC lookup (no open dataset is bundled; the response says bankLookup: false). National check digits are applied only where a public algorithm exists (FR, ES, IT, BE, NL for ABNA/INGB/RABO, NO, FI, PL, PT, RS, ME, MK, XK, SI); other countries report not-available. Germany has no general national algorithm.
/api/lei	GLEIF Global LEI Index	CC0 public domain. No key.
/api/recalls	openFDA enforcement reports (food, drug, device) and the CPSC SaferProducts.gov Recall API	openFDA data is public domain under its terms of use (not for medical decisions). CPSC does not classify recalls: its severity is derived from the hazard text, FDA Class I/II/III maps to high/medium/low.
/api/violations	US Department of Labor Data API v4 (OSHA) and EPA ECHO	US government works. OSHA needs the optional DOL_API_KEY secret: without it the route returns EPA only and says OSHA is off. Records are matched by name and show inspections and cases, not guilt.
/api/uk-insolvency	The Gazette, through our own nightly cache (gazette-cache.sitecheck-api.workers.dev, last 8 UK days). The Gazette is never called directly.	Open Government Licence v3.0. Answers carry the cache's dataTimestamp and any missingDays. Optional Companies House enrichment (status, incorporation date, SIC codes, address; at most 10 rows per call) when COMPANIES_HOUSE_API_KEY is set.

Workers limits are respected: every upstream call has a timeout (at most 10 s) and a SiteCheck/1.x User-Agent, every tool stays well under 50 subrequests, and nothing large is parsed per request (the Gazette text is scanned and only matching notices are parsed). Stable upstream answers are cached with the Cache API where it works.

curl -s "https://api.sitecheck-api.workers.dev/api/vat?number=DE811907980"        # 402 first: pay with any x402 client

MCP server

https://api.sitecheck-api.workers.dev/mcp is a remote MCP server (Streamable HTTP, stateless, JSON answers). Every paid endpoint is an MCP tool with the same input schema (read, pdf, tech, email_check, domain, solana_token, vat, lei, ...), and the same price.

Payment uses the x402 MCP transport: a tools/call without payment returns isError with the x402 PaymentRequired object in structuredContent; the client signs one option and repeats the call with the PaymentPayload in params._meta["x402/payment"]; the answer carries the settlement in result._meta["x402/payment-response"]. A tool call that fails is not settled. Each call is replayed inside the Worker against the matching /api route, so MCP and HTTP buyers go through the same payment checks.

import { createx402MCPClient } from "@x402/mcp";
import { ExactEvmScheme } from "@x402/evm/exact/client";
import { StreamableHTTPClientTransport } from "@modelcontextprotocol/sdk/client/streamableHttp.js";

const client = createx402MCPClient({
  name: "my-agent", version: "1.0.0",
  schemes: [{ network: "eip155:8453", client: new ExactEvmScheme(account) }], // a viem account holding USDC on Base
  autoPayment: true,
});
await client.connect(new StreamableHTTPClientTransport(new URL("https://api.sitecheck-api.workers.dev/mcp")));
const page = await client.callTool("read", { url: "https://docs.x402.org/introduction" }); // pays $0.002

MCP clients without x402 support (for example a plain remote connector) can list the tools and see each price, but a call returns the payment requirements instead of a result.

Networks

Network	CAIP-2	USDC	Facilitator
Base	eip155:8453	0x8335…2913	PayAI
Solana	solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp	EPjF…Dt1v	PayAI
Arc	eip155:5042	0x3600…0000	Circle Facilitator Service

The price is the same on every network. Buyers need only USDC: EVM payments are EIP-3009 signatures, and the facilitator pays gas and Solana fees. Sources and design decisions: docs/NETWORKS.md.

Try it

curl -si "https://api.sitecheck-api.workers.dev/api/audit?url=example.com" \
  | grep -i '^payment-required:' | cut -d' ' -f2 | tr -d '\r' | base64 -d
# {"x402Version":2,"error":"Payment required", ..., "accepts":[{ "network":"eip155:8453", "amount":"20000", ... }, ...]}

Pay with any x402 client. Base or Arc, with @x402/fetch and a viem account:

import { wrapFetchWithPayment, x402Client } from "@x402/fetch";
import { ExactEvmScheme } from "@x402/evm/exact/client";
import { privateKeyToAccount } from "viem/accounts";

const account = privateKeyToAccount(process.env.EVM_PRIVATE_KEY);  // holds a little USDC
const client = x402Client.fromConfig({
  schemes: [{ network: "eip155:8453", client: new ExactEvmScheme(account) }],   // Arc: "eip155:5042"
  // Arc only: its USDC is not in @x402/evm's built-in asset list yet, so opt in (cap: $0.10 per call).
  // spendControls: { allowedAssets: [{ network: "eip155:5042", asset: "0x3600000000000000000000000000000000000000", maxAmountPerPayment: "100000" }] },
});
const pay = wrapFetchWithPayment(fetch, client);
const res = await pay("https://api.sitecheck-api.workers.dev/api/audit?url=example.com");
console.log(await res.json());

Solana, with @x402/svm and a @solana/kit signer:

import { readFileSync } from "node:fs";
import { wrapFetchWithPayment, x402Client } from "@x402/fetch";
import { ExactSvmScheme } from "@x402/svm/exact/client";
import { createKeyPairSignerFromBytes } from "@solana/kit";

const signer = await createKeyPairSignerFromBytes(Uint8Array.from(JSON.parse(readFileSync("buyer.json", "utf8"))));
const client = new x402Client().register("solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp", new ExactSvmScheme(signer));
const pay = wrapFetchWithPayment(fetch, client);
console.log(await (await pay("https://api.sitecheck-api.workers.dev/api/audit?url=example.com")).json());

Every endpoint declares its input schema and an output example through the x402 Bazaar discovery extension, so agents can find and call it without reading docs.

Demo agent

scripts/demo-agent.mjs discovers the API through /.well-known/x402, pays for one audit on the network you pick, and prints the result and the transaction link:

node scripts/demo-agent.mjs --network base     # or arc, solana

On the first run it creates a throwaway wallet in a git-ignored file (.env.evm for Base and Arc, .env.solana for Solana) and prints its address. Fund it with about 0.10 USDC on that network; one audit costs 0.02 USDC, and no ETH or SOL is needed. --dry-run stops before paying, and --url points it at another deployment.

Design notes

• Pay only for results. The settlement runs after the handler. If a model or upstream fails, the handler returns an error status and the payment is not settled, so the buyer isn't charged. This holds on all three networks and is covered by the tests.
• One route, several networks. Each route lists one x402 accepts entry per configured network. Base and Solana settle through PayAI. Arc settles through Circle's Facilitator Service on its keyless trial: each request carries a seller proof signed by the Arc receiving wallet's key (see below). Each facilitator client only reports the networks assigned to it (lib/payments.js).
• Workers-safe x402 middleware. A Worker can't await a promise created by another request, and the x402 middleware initialises lazily. Each request builds and initialises its own middleware until one has finished; that one is then reused (lib/app.js).
• No keys in the repo. Receiving addresses live in wrangler.toml [vars] (empty by default). The Arc seller key (or, as a fallback, the Circle API key) is a Worker secret. The helper scripts keep their wallets in git-ignored .env.* files.

Arc: Circle's keyless trial and a hot wallet

Circle's Facilitator Service normally needs an API key, and on mainnet that needs a Circle account with a credit card on file. SiteCheck uses Circle's keyless trial instead. Every /verify and /settle request carries a Facilitator-Seller-Proof header: an EIP-712 signature by the key that controls Arc's payTo, bound to the route, the exact request body and a fresh nonce (lib/sellerProof.js, lib/circle.js).

The trade-off: that key has to live in the Worker, as the secret ARC_SELLER_KEY. So Arc's payTo is a dedicated hot wallet that only receives payments. The owner sweeps it to a cold wallet regularly (scripts/sweep-arc.mjs), so a leaked key would expose at most what came in since the last sweep. The trial allowance is also limited, and Circle doesn't publish it. When it runs out, Circle answers 403 registration_required. The payment is not settled and the buyer is not charged, the Worker logs it, and GET /health shows arc.trialExhausted: true. From then on, Arc needs a Circle API key or has to be switched off. Details: docs/NETWORKS.md.

Run your own

npm install
npm test                    # no network needed: the facilitators and Panta are mocked
npx wrangler dev            # local

Deploy: set account_id and at least one receiving address in wrangler.toml (or pass it with --var). For Arc, create the hot wallet and store its key first:

node scripts/new-arc-wallet.mjs            # Arc only: prints the new address; the key goes to .env.arc-seller
npx wrangler secret put ARC_SELLER_KEY     # paste the key from .env.arc-seller
npx wrangler secret put PANTA_API_KEY      # optional: a pk_live_... key switches the prediction-market tools on
npx wrangler secret put DOL_API_KEY        # optional: switches OSHA on in /api/violations
npx wrangler secret put COMPANIES_HOUSE_API_KEY   # optional: enriches /api/uk-insolvency rows
npx wrangler deploy
node scripts/sweep-arc.mjs --to 0xYourColdWallet          # later, regularly: shows what it would send
node scripts/sweep-arc.mjs --to 0xYourColdWallet --yes    # sends it

Variable	Network	Notes
PAY_TO	Base	EVM address
PAY_TO_SOLANA	Solana	wallet address; it must already have a USDC token account
ARC_SELLER_KEY (secret)	Arc	private key of the dedicated Arc receiving wallet; switches Arc on and sets its payTo
PAY_TO_ARC	Arc	optional with ARC_SELLER_KEY (if set, it must equal the key's address); without a seller key, the Arc address to use with CIRCLE_API_KEY
CIRCLE_API_KEY (secret)	Arc	fallback only, used when ARC_SELLER_KEY is not set
FACILITATOR_URL	Base, Solana	default https://facilitator.payai.network
FACILITATOR_URL_ARC	Arc	default https://api.circle.com/v1/facilitator/x402
PANTA_API_KEY (secret)	all	switches the prediction-market tools on: npx wrangler secret put PANTA_API_KEY (see docs/PANTA.md)
PANTA_BASE_URL	all	default https://live-api.panta.market/api/v1
DOL_API_KEY (secret)	all	optional: switches OSHA on in /api/violations: npx wrangler secret put DOL_API_KEY. Without it the route is EPA only
COMPANIES_HOUSE_API_KEY (secret)	all	optional: Companies House enrichment in /api/uk-insolvency: npx wrangler secret put COMPANIES_HOUSE_API_KEY

Leave an address empty to switch that network off. GET /health shows which networks are active and why the others are not, and whether the Panta tools are on. For Arc it also shows the auth mode, the receiving address and the trial status.

License

MIT

Mainnet transactions

Real x402 settlements on all three networks:

• Solana (our test): https://solscan.io/tx/4DQcTjw791d83iUFU7NBbyi3JZxXsvHbNHWgcXb9eeVT4tqReDV4ZFqYanUpJXnGP2ogucsWHqehioJd6Dq1ghDJ
• Base (our test): https://basescan.org/tx/0xf4e4a1aeeff698706e49cd921321cda9dba79babefd00b624bdf836fda57beb1
• Arc (our test): https://explorer.arc.io/tx/0xb6abceb6108099730c31b00f9140288585a869029bc5c922b88f0df5e8289476
• Base, paid by an outside AI agent we don't control (one of its 12 paid calls so far): https://basescan.org/tx/0x9e37d0287f04f7c1f89f159f839c0f391230dab6c21aeead58d6a29588239ea9
• Base, paid by a second outside wallet (6 Oct 2026): https://basescan.org/tx/0x9d5f1cae2c5016f165eead7dc56f51a3d74a1ea90a06270d4b0ca8bf97d8d211