Meld

@openrampkit/adapter-meld gets fiat onramp quotes from many providers through Meld, picks the best one, and sends the user to that provider's widget.

New adapter

This adapter is new and still in progress. Some provider details are marked TO VERIFY in the source (listed below).

import { meld } from '@openrampkit/adapter-meld'

meld({
  apiKey: process.env.MELD_API_KEY!,
  env: 'production',
  webhookSecret: process.env.MELD_WEBHOOK_SECRET,
})

To get the keys, see Get provider keys.

Options

Option	Type	Default	Description
apiKey	string	required	Sent as Authorization: BASIC <apiKey>
env	'sandbox' | 'production'	required	Sandbox is https://api-sb.meld.io. The server checks env against livemode.
serviceProviders	string[]	all on your account	Only quote these providers, e.g. ['TRANSAK', 'BANXA']
webhookSecret	string	none	Webhook profile secret. Without it, webhooks are rejected.
webhookUrl	string	the request URL	The URL registered in the Meld profile (the signature covers it). Set it when a proxy rewrites URLs.
deliverAssets	MeldDeliverAsset[]	USDC on Base, Ethereum, Polygon, Arbitrum	Assets to buy, most preferred first. A destination token that is not in the list gets no quote (NO_QUOTES).
defaultCountry	string	'US'	Country for quotes when the session has none
version	string	'2026-02-03'	Meld-Version header
apiUrl	string	by env	API base URL

Legs

One leg per payment method. Static legs (used when the catalog fails): card, apple_pay, google_pay, upi (IN, INR), pix (BR, BRL), binance_pay, sepa (EUR countries), ach (US, USD), and these regional methods:

Leg and method	Meld code	Countries	Fiat
sepa_instant	SEPA_INSTANT	EUR countries	EUR
faster_payments	UK_FASTER_PAYMENTS (the catalog also maps FPS)	GB	GBP
open_banking	OPEN_BANKING	EU, GB, IS, LI	any
ideal	IDEAL	NL	EUR
bancontact	BANCONTACT	BE	EUR
blik	BLIK	PL	PLN
payid	PAYID	AU	AUD
interac	INTERAC	CA	CAD
spei	SPEI (the catalog also maps STP)	MX	MXN
pse	PSE	CO	COP
khipu	KHIPU	CL	CLP
imps	IMPS	IN	INR
mpesa	MPESA	KE	KES
mobile_money	MOBILE_MONEY	29 countries in Africa and Asia	any

The catalog also maps SOFORT, ASTROPAY, PAYPAL, VENMO, CASH_APP, ZELLE, REVOLUT_PAY, REVOLUT and MERCADOPAGO. Meld lists the codes and their countries on its payment method coverage page (read on 2026-10-04). The live catalog (GET /service-providers/properties/payment-methods, cached for an hour per country and currency) builds the legs for the user's country and currency.

• Surface: REDIRECT to the chosen provider's widget (serviceProviderWidgetUrl, else Meld's hosted widgetUrl). The modal shows the provider's name.
• Delivers to deliverTo.address (a hop) or the destination address.

Quotes and start

• Quote: POST /payments/crypto/quote returns one quote per provider. The one with the most crypto out is the leg quote. The full list is in quote.data.providers. The guarantee is estimate: the chosen provider sets the final price. Quotes expire after 5 minutes (quoteExpiresAt(5)).
• Fees, in the fiat currency, all with included: true: the provider's transactionFee (provider), networkFee (network) and partnerFee (app).
• Start: POST /crypto/session/widget (sessionType: 'BUY') with the chosen provider, the wallet, the amount, redirectUrl, the user's IP when known, externalCustomerId (the user id) and externalSessionId (the leg ref, ork_{random}).
• Status: GET /payments/transactions?externalSessionIds={ref}.
• providerRef: the Meld transaction id. Meld gives it once the user starts to pay, so the start step has none.
• Transactions: a settled transaction's hash is the destination transaction.

Meld status	Leg
SETTLED	succeeded
PENDING_CREATED, TWO_FA_REQUIRED	requires_action
PENDING, TWO_FA_PROVIDED, ACCEPTED, AUTHORIZED	processing, detail code processing
SETTLING, PARTIALLY_SETTLED	processing, detail code settling
ERROR	processing, detail code delayed (ERROR is temporary at Meld)
FAILED, DECLINED, CANCELLED, AUTHORIZATION_EXPIRED	failed
REFUNDED	refunded
other	no event: the adapter logs the unknown status once (statusMap), and the leg keeps its current step

Webhooks

Create a Meld webhook profile with the URL {baseUrl}/webhooks/meld and pass its secret as webhookSecret.

• Verification: Meld-Signature is the base64url (with padding) HMAC-SHA256 of {Meld-Signature-Timestamp}.{webhookUrl}.{body}. The adapter checks it with verifyTimestampedHmac from @openrampkit/adapter.
• Only TRANSACTION_CRYPTO_* events are read. On a settled event, the adapter reads the transaction for the amount and the transaction hash.

Verified vs TO VERIFY

• Verified: the USDC (Ethereum) and USDC_BASE currency codes.
• TO VERIFY: USDC_POLYGON and USDC_ARBITRUM.
• TO VERIFY: the UPI and BINANCE_PAY payment method codes. The coverage list has BINANCE_P2P and BINANCE_CASH_BALANCE, not BINANCE_PAY.
• TO VERIFY: MERCADO_PAGO. The coverage list spells it MERCADOPAGO, and the adapter sends that spelling.
• TO VERIFY: Meld documents no timestamp tolerance for webhooks. The adapter rejects timestamps more than 5 minutes off.