Using 402arcade from agent payment frameworks
402arcade is an x402 v2 merchant: 12 pay-per-call data and web APIs priced $0.003–$0.02 in USDC on Base. This guide covers allowlisting it in controlled-spend frameworks like AWS AgentCore Payments (per the OpenAI/AWS agentic-commerce cookbook) and calling it from any x402 client SDK.
1 — Develop against the free sandbox
The sandbox at https://sepolia.402arcade.dev is byte-identical to production but settles on Base Sepolia with worthless test USDC (grab 20 free from Circle's faucet, network: Base Sepolia). Your integration test suite can make real paid calls for $0.00.
# the 402 challenge — same shape on sandbox and production curl -i "https://sepolia.402arcade.dev/base/balance?address=0x849151d7D0bF1F34b70d5caD5149D28CC2308bf1" # → HTTP 402, payment-required: <base64 envelope: amount, payTo, network, schemas>
2 — Allowlist in a controlled-spend policy
Frameworks like AgentCore separate the agent (decides when to buy) from the application (decides whether). 402arcade fits standard policy shapes:
| policy field | value for 402arcade |
|---|---|
| merchant host | 402arcade.dev (sandbox: sepolia.402arcade.dev) |
| max price per call | 0.02 USDC covers every endpoint; most are ≤ 0.005 |
| network | eip155:8453 (sandbox: eip155:84532) |
| asset | USDC (0x8335…2913 on Base) |
| settlement | Coinbase x402 facilitator; on-chain receipt (tx hash) in payment-response header |
Prices are stable — approvals that pin an exact amount won't drift under you. Every response settles with an on-chain transaction hash your application can log for audit.
3 — Or call directly from any x402 client
import { x402Client, wrapFetchWithPayment } from "@x402/fetch";
import { ExactEvmScheme } from "@x402/evm/exact/client";
import { privateKeyToAccount } from "viem/accounts";
const client = new x402Client();
client.register("eip155:*", new ExactEvmScheme(privateKeyToAccount(KEY)));
const payFetch = wrapFetchWithPayment(fetch, client);
const risk = await payFetch("https://402arcade.dev/base/rugcheck?token=0x…");
What's on the floor
Base onchain data (balances, portfolios, basenames, NFTs, transactions), best-execution DEX quotes, token safety screening, cross-protocol identity, webpage→markdown/screenshot/PDF, and a batch endpoint. Full machine-readable catalog: openapi.json · llms.txt · catalog.