Pay-in API (card / bank → Base USDC)

Public endpoints that quote and start card/bank checkout into USDC on Base (8453). Used by /buy, invoice card checkout on /pay, and wallet cash-in.

Requires MetaMask pay-in enabled on the instance (METAMASK_ONRAMP_ENABLED, default on). Checkout opens in a new tab at the provider (MoonPay, Banxa, Ramp, Coinbase). There is no create-time quote and no Onramper session.

Fiat and combined invoices settle as Base USDC. Crypto-only invoices stay multi-chain.

`GET /api/public/pay-in/config`

Instance capability probe.

{
  "enabled": true,
  "chainId": "8453",
  "token": "USDC",
  "tokenAddress": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913"
}

`GET /api/public/pay-in/countries`

Regions MetaMask can quote (id, name, default fiat).

`GET /api/public/pay-in/geo`

Payer country from CDN/edge IP headers (CF-IPCountry, x-vercel-ip-country, …). The UI prefers Cloudflare’s browser cdn-cgi/trace (client IP) and uses this as fallback. Query country= still overrides.

{ "country": "LT" }

`GET /api/public/pay-in/quotes`

Query	Notes
`region` or `country`	MetaMask region id (`de`, `us-mi`)
`fiat`	e.g. `EUR`
`amount`	Fiat to spend
`address` or `walletAddress`	Destination EVM wallet (required)

Response includes quotes[] with provider, payment method, USDC out, and fees. All listed providers can be opened in a new tab.

`GET /api/public/pay-in/widget`

Returns { widgetUrl, embeddable, provider, orderId } for the chosen quote. The UI opens widgetUrl in a new tab (popup-safe: blank tab on click, then navigate).

Query	Notes
`region`, `fiat`, `amount`, `address`	Same as quotes
`providerId`	e.g. `/providers/moonpay`
`paymentMethodId`	e.g. `/payments/debit-credit-card`

GET /api/public/pay-in/buy-url is an alias of this route.

Card funding an invoice

Create a fiat or combined invoice with price (USDC), chains: ["8453"], tokens: ["USDC"]. Optional displayFiat / displayAmount / quoteCountry are payer hints only.
Payer opens /pay?id=… (crypto QR still works for combined) or /buy?address={invoiceAddress}&amount=…&fiat=EUR&country=de&invoice={id}.
Continue fetches the widget URL and opens provider checkout in a new tab.
Poll GET /api/invoices/{id} until paid — funding is detected on invoiceAddress; there is no onramp-session webhook.

Direct buy (no invoice): /buy?address=0x…&amount=100&fiat=SEK&country=se.

Rate limits

Pay-in routes use the dedicated quote bucket (default 2/s sustained, burst 20 per IP). Exceeding returns 429 with Retry-After, RateLimit-Remaining, and RateLimit-Reset. See HTTP API — Rate limiting.