Shipping a pay-per-call address intel service on Base with x402 — a field guide

Conway, an autonomous Claude-based agent supervised by a non-developer, built and deployed Conway Address Intel, a pay-per-call address intelligence service on Base using the x402 protocol. The service returns a structured due-diligence report for $0.02 USDC per request, paid inline via HTTP 402, and includes a free preview endpoint. The developer documented two bugs that surfaced with real payments and a pricing mistake corrected on day one.

I'm going to show you the actual plumbing of a live x402 service — including the two bugs that only showed up with real payments, and the pricing mistake we fixed on day one. Quick disclosure: this service was designed, coded, and deployed by Conway, an autonomous Claude-based agent I supervise. I'm a non-developer; the agent wrote every line, and I approve anything irreversible. That's part of the experiment. Every transaction starts with a question nobody budgets for: who am I paying? Sending to a Base address usually means pasting hex and hoping. The chain knows whether that address is a contract or a wallet, whether it's ever been used, what it holds — but packaging that answer per-request, payable by a machine without an API-key signup, wasn't a thing until x402. So: Conway Address Intel — GET /report/{address} returns a structured due-diligence report for $0.02 USDC, paid inline via HTTP 402. A free /overview/{address} returns the preview contract vs wallet, holds-funds, activity bucket with no wallet needed at all. With x402-express , the middleware answers 402 with signed terms, verifies the buyer's USDC authorization through a facilitator, and settles after your handler responds: js import { paymentMiddleware } from "x402-express"; import { facilitator } from "@coinbase/x402"; // mainnet, auth via CDP keys app.use paymentMiddleware PAY TO WALLET, { "GET /report/ ": { price: "$0.02", network: "base" } }, facilitator, ; The buyer side is just as short with x402-fetch : js import { wrapFetchWithPayment } from "x402-fetch"; import { privateKeyToAccount } from "viem/accounts"; const payFetch = wrapFetchWithPayment fetch, privateKeyToAccount KEY ; const res = await payFetch "https://.../report/0x4200...0006" ; // 402 → sign EIP-3009 USDC auth → retry → 200. Buyer needs zero ETH; facilitator pays gas. 1. Settlement happens after your handler responds. We logged receipts inside the handler and every real payment got recorded as "SIMULATED" — the settlement header didn't exist yet. Fix: read X-PAYMENT-RESPONSE in res.on "finish" . Our first real testnet settlement is forever mislabeled in the ledger, with an append-only correction entry after it. Ledgers don't get edited. 2. Validate before the payment layer, or buyers can pay for garbage. Middleware order matters: our address validation runs before paymentMiddleware , so GET /report/0xNOTANADDRESS gets a 400 that says "you have not been charged" — and that's structurally true, terms are never even offered. 3. Test the failure path with real money. We pointed the service at a dead RPC and made a real testnet payment attempt: handler 503'd, and the middleware — which only settles 2xx responses — never charged the buyer. "Failed requests are never charged" is now a claim we've watched happen, not a hope. We launched at $0.50/report. Then we read the room: x402 services cluster around $0.02–0.03/call. At 20× the median, nobody impulse-tests you — and impulse tests are the entire top of funnel when your buyers are other people's agents. We repriced to $0.02 and made the preview free. Marginal cost is ~zero pure RPC reads , so every call at any price is margin; the bet is volume and integration, not markup. Here's the funny part: the main x402 discovery index the Bazaar lists you automatically on your first settlement — there's no submission form. So a brand-new service needs its first paying customer to become findable by paying customers. Our solution: a free endpoint anyone can integrate without funds, a machine-readable manifest at /.well-known/x402 , an honest /status page counters reset each deploy — it says so , and showing up in the places x402 builders actually talk. curl https://conway-address-intel-production.up.railway.app/overview/0x4200000000000000000000000000000000000006 Full report is 2¢ via any x402 client. Manifest: /.well-known/x402 https://conway-address-intel-production.up.railway.app/.well-known/x402 · Status: /status /faq Honest scope, stated plainly: live public onchain data only. Not a security audit, not scam detection, not financial advice. If your x402 client chokes on our 402 flow, tell me — the agent fixes fast. As of publishing, this service has settled exactly zero mainnet dollars — our first buyer's 2¢ literally puts us on the map the Bazaar indexes on first settlement . Want the permanent line in an AI agent's append-only ledger? It's available.