How to Add Stablecoin Checkout to Your Website with a Payment API

Keep your order system and use hosted checkout

You can add stablecoin payments without building every payment screen yourself. With a payment API and hosted checkout, your website creates an invoice from a trusted order, sends the customer to its payment page, and waits for verified payment evidence before completing the sale.

Your store still owns its prices, inventory, customer service, and fulfillment rules. Ulasend provides the invoice and payment workflow. That division gives your developer a clear integration boundary, whether you operate a custom storefront or another application. Start by confirming your merchant approval and receiving setup; an API key alone does not enable live processing.

Create the payment from a trusted order

Your server should calculate and save the order total before requesting an invoice. A price typed into a browser field or appended to a URL is not enough to establish what the customer owes. Keep the expected amount, order reference, and relevant order state in your own system.

Create the invoice from your backend, keeping the API key out of browser code. Save the returned invoice ID with your order so later notifications can be matched precisely. Use the documented idempotency mechanism when retrying requests to avoid creating unintended duplicate invoices. The Ulasend quickstart shows this sequence.

Send the customer to the issued checkout URL

Use the checkout URL returned by the API. The payment page presents the configured asset, network, amount, destination, and available payment controls. An existing invoice keeps its original source instructions; it is not a universal address for any coin or blockchain.

For reusable crypto payment links, a secure checkout session can bind a particular order and amount to a short-lived URL. Ordinary reusable links and signed order sessions serve different needs. Your developer should follow the dynamic payment links guide rather than trusting a buyer-editable amount.

Decide exactly what authorizes fulfillment

A customer reaching a success page is useful for navigation, but it is not proof that the required funds arrived. The server must verify the payment notification and current invoice evidence before releasing goods, activating access, or starting an automated delivery.

For custom API integrations, a deliberately accepted shortfall must satisfy the rule saved on that invoice. Ulasend's published commerce integration previews require the full saved invoice quote even if the account permits small shortfalls. Confirm which rule your integration implements before launch.

Build the decision around the webhook fulfillment checks. Your integration should:

• Verify the webhook signature before trusting its contents.
• Match the invoice and saved order reference, and confirm that a real order has live payment evidence.
• Check the current payment status, settlement asset, and actual received amount against the final saved quote and applicable payment policy.
• Record fulfillment once so repeated notifications cannot ship an order or grant access twice.

Test delays and mistakes before going live

A successful test payment is only the beginning. Ask your developer to test an abandoned checkout, an expired invoice, a short payment, repeated notifications, and a delayed payment confirmation. Each case should leave the customer with a clear status and your business with an accurate order record.

Keep test orders, stock changes, emails, and fulfillment separate from real commerce. A test-mode payment must never authorize a real shipment. Decide who reviews exceptions and how that person can find the original invoice without relying on a screenshot supplied by the buyer.

Check your platform's actual integration status

A custom API integration and an installable store plugin are different products. Ulasend's published commerce integrations are development previews with their own limits and testing requirements. Shopify merchant installation is not currently available; review the current Shopify status before planning an installation.

Review the integration overview with your developer before choosing an approach. Define one complete payment journey first, including exceptions and reconciliation. A smaller integration that verifies every order is a better starting point than enabling payment controls before the order-handling process is ready.