Create a merchant account at app.asterpay.io/signup. Sumsub KYB takes 30 minutes for a typical EU-incorporated entity. You provide entity name, registration number, beneficial owners and the IBAN where EUR settlements should land.
From the dashboard generate an API key. Store as ASTERPAY_API_KEY in your backend environment. Never expose it to a frontend or an agent prompt.
One line of middleware. AsterPay ships drop-in middleware for Express, Fastify, FastAPI and Next.js. Example for Express:
import { asterpay } from '@asterpay/x402-express';
app.get('/api/forecast',
asterpay({ priceEur: 0.05, settlementIban: process.env.MY_IBAN }),
(req, res) => res.json({ forecast: '...' })
);
The agent receives the 402, signs an EIP-3009 transferWithAuthorization for USDC on its preferred chain (Base, Polygon, Arbitrum, Optimism, Ethereum or Solana), and resends the request with the X-PAYMENT header. Any x402-aware agent SDK does this automatically — x402-fetch, the AsterPay MCP server, the Coinbase x402 client. No agent-side configuration needed.
AsterPay verifies the payment proof, runs KYA trust scoring on the agent wallet, executes the on-chain settlement, swaps USDC to EUR through a licensed European payment partner (auto-routed by amount, currency and partner availability), and pushes EUR to your IBAN via SEPA Instant. End-to-end under 15 seconds in normal conditions. Specific partner identities are disclosed to onboarded customers under partnership-only disclosure terms.
Each settlement returns a Payment-Receipt header with the on-chain tx hash, the SEPA reference, the EUR amount net of fees, and the FX rate at moment of swap. Feed it into your accounting software for clean EUR-denominated journal entries. No FX drift, no double bookkeeping, no monthly stablecoin reconciliation spreadsheet.
Sample EU SaaS with 3,000 agent calls per day at EUR 0.05 each: roughly EUR 4,500 monthly settlement. With AsterPay all 4,500 EUR lands in the merchant's IBAN as 90,000 individual SEPA Instant credits aggregated into a single daily payout (configurable). Total fees at 100 bps all-in: EUR 45/month. Compare to Stripe card processing at the same volume: EUR 4,500 × 1.4% + 25c per transaction = EUR 63 + EUR 22.50 = EUR 85.50/month, plus the chargeback risk that does not exist for x402 payments.
The same flow works for SEPA-area merchants (36 countries including the UK, Norway, Switzerland and Liechtenstein). For US merchants, USD via ACH is on the roadmap; for UK merchants, GBP via Faster Payments is on the roadmap. Outside SEPA, AsterPay can still settle USDC to USDC at your wallet address — you skip the EUR conversion but keep the KYA trust filter, the multi-chain ingress and the dual x402+MPP support.