x402centre

Machines: read /catalog, then pay.

This page is for agents. Every number below is also machine-readable at the free endpoints — trust the JSON, not the prose.

Key	Value
Discovery (free)	GET /catalog — full menu, prices, atomic units, how to pay
x402 discovery doc	GET /.well-known/x402
Liveness (free)	GET /healthz, GET /live/state/beacon
Protocol	x402 v2, scheme exact, EIP-3009
Network	eip155:8453 (chainId 8453, Base)
Asset	USDC 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 (6 decimals; $0.10 = 100000)
Facilitator	https://x402.org/facilitator
payTo	0xAA08C81A382E0a1F9b472E93c894330205b4FfE6

Minimal client (Bun/Node)

import { wrapFetchWithPaymentFromConfig, decodePaymentResponseHeader } from "@x402/fetch";
import { ExactEvmScheme } from "@x402/evm";
import { privateKeyToAccount } from "viem/accounts";

const account = privateKeyToAccount("0x…");
const fetchWithPayment = wrapFetchWithPaymentFromConfig(fetch, {
  schemes: [{ network: "eip155:8453", client: new ExactEvmScheme(account) }],
});
const res = await fetchWithPayment("https://x402centre.roverbot.workers.dev/research/gas");
const settle = decodePaymentResponseHeader(res.headers.get("PAYMENT-RESPONSE"));
// settle.transaction = onchain tx; verify on the Base explorer (basescan.org)

Rules of the road

402 = pay. 400 = you malformed a header. 500 = our fault — the payment did not settle.
429 = you're hammering the verify endpoint; back off 60s.
Every 402 carries the full offer (amount, asset, payTo, window) in PAYMENT-REQUIRED — read it, don't assume.
Nonces are one-shot. A failed settlement returns the reason in PAYMENT-RESPONSE; a settlement_pending reason means the tx may still confirm — check before retrying.
?format=json returns structured {title, asOf, sections, settle} — the agent-native surface.