Use a single integration to accept payments through one-click payment buttons. The Express Checkout component is a Fintoc SDK feature that lets your customers pay with wallet buttons, without opening the full widget. The currently supported payment method is Apple Pay. Customers see the Apple Pay button depending on their device and browser. If Apple Pay is not available on the device, the button is hidden.

Before you begin: your domain must be enabled for Apple Pay. Apple Pay won’t load until Fintoc registers your domain with Apple, so the button stays hidden on an unregistered domain. See Enabling Apple Pay to start the process before you integrate.

Accepting Apple Pay payments with Express Checkout takes six steps:

Set up your server to create a Checkout Session
Set up the Fintoc SDK on your frontend
Create and mount the Express Checkout component
Handle the onPaymentRequest callback
Submit the payment to Fintoc
Test the integration

Step 1: Set up your server

Server-side

Express Checkout calls the onPaymentRequest callback after the customer authorizes the Apple Pay sheet. In that callback you must create a Checkout Session from your backend and return its session_token to the browser. Expose an endpoint on your server that creates a Checkout Session with Fintoc’s API: Node

// server.js (Node example)
app.post("/api/create-checkout", async (req, res) => {
  const response = await fetch("https://api.fintoc.com/v2/checkout_sessions", {
    method: "POST",
    headers: {
      Authorization: process.env.FINTOC_SECRET_KEY,
      "Content-Type": "application/json",
    },
    body: JSON.stringify({
      amount: 1000,
      currency: "CLP",
      payment_methods: ["card"],
      recipient_account: { id: "acc_a1b2c3d4e5" },
      // ...any other fields your flow requires
    }),
  });

  const session = await response.json();
  res.json({ session_token: session.session_token });
});

Never expose your secret key in the browser. Always keep the Checkout Session creation call on your server.

Step 2: Set up the Fintoc SDK

Client-side

Express Checkout is automatically available as a feature of the Fintoc SDK. Include the Fintoc script on your checkout page by adding it to the <head> of your HTML file. Always load the SDK directly from js.fintoc.com to receive security updates. Don’t include the script in a bundle or host a copy of it yourself.

<head>
  <title>Checkout</title>
  <script src="https://js.fintoc.com/v1/"></script>
</head>

Step 3: Create and mount the Express Checkout

Client-side

The Express Checkout component renders the wallet button inside an iframe that securely sends the payment information to Fintoc over an HTTPS connection. The checkout page address must also start with https://, rather than http://, for your integration to work. First, create an empty DOM node (container) with a unique ID in your payment form:

<div id="apple-pay-container">
  <!-- Express Checkout will be inserted here -->
</div>
<div id="error-message">
  <!-- Display an error message to your customers here -->
</div>

When the form has loaded, create an instance of the widget and mount Express Checkout to the container DOM node:

const widget = window.Fintoc.create({
  product: "payments",
  publicKey: "pk_test_...",
  country: "cl",

  expressCheckout: {
    container: "apple-pay-container",
    amount: 1000,
    currency: "CLP",
  },

  onPaymentRequest: async ({ payment_method_type, wallet }) => {
    const res = await fetch("/api/create-checkout", { method: "POST" });
    const { session_token } = await res.json();
    return { sessionToken: session_token };
  },

  onSuccess: (data) => console.log("Payment succeeded", data),
  onExit: (reason) => console.log("Widget closed", reason),
  onEvent: (eventName, metadata) => console.log(eventName, metadata),
});

The Apple Pay buttons can have the following styles:

Step 4: Handle the onPaymentRequest callback

Client-side

onPaymentRequest runs when the SDK needs a sessionToken to continue the flow. For Apple Pay, the SDK calls it after the customer authorizes the Apple Pay sheet. When you call widget.open() for bank transfer, the SDK calls the same callback before it opens the widget. In that callback you must call your server, obtain a session_token, and return it to the SDK. The callback receives a single argument with information about the requested method:

Field	Type	Description
`payment_method_type`	`string`	`"card"` for wallet payments. `"bank_transfer"` when `widget.open()` is called.
`wallet`	`string` (optional)	The specific wallet selected, e.g. `"apple_pay"`. `undefined` for bank transfer.

Your callback must resolve to { sessionToken: string } within 30 seconds, or the SDK emits payment_error.

You can use the payment_method_type and wallet fields to reuse a single endpoint for wallets and bank transfer, or to route to different endpoints if your backend logic differs.

Step 5: Submit the payment to Fintoc

Client-side

Once the customer authorizes the wallet payment, the SDK automatically completes the flow. You don’t need to call a confirmPayment method yourself. The sequence is:

The SDK opens the Apple Pay sheet and requests a payment token from Apple Pay.
Once the customer authorizes, the SDK emits processing_express_checkout_payment.
The SDK calls your onPaymentRequest callback to get a fresh sessionToken.
The SDK submits both tokens to the Fintoc backend, which creates the Payment Resource and charges the wallet.
When the payment reaches status === 'succeeded', the SDK calls onSuccess(data) with the resulting resource.

If the payment status is anything other than succeeded, or any step in the flow fails, the SDK emits payment_error instead of calling onSuccess.

Handling the loading state during payment processing

While Express Checkout is processing a payment, you should display a loading state to give clear feedback to your customer and prevent duplicate interactions. Manage it from the onEvent and onSuccess callbacks you already pass to Fintoc.create:

processing_express_checkout_payment fires once the customer authorizes the payment. Use it to show your loading indicator while the SDK gets a fresh sessionToken from your server and submits the payment.
The payment then resolves through onSuccess when it succeeds, or through a payment_error event when it fails. Use both to clear the loading indicator.

A typical implementation looks like this:

window.Fintoc.create({
  // ...
  onEvent: (eventName) => {
    if (eventName === "processing_express_checkout_payment") {
      // Show loading state (e.g. spinner, disable buttons)
      setLoading(true);
    }
    if (eventName === "payment_error") {
      // Hide loading state after a failed attempt
      setLoading(false);
    }
  },
  onSuccess: () => {
    // Hide loading state after a successful payment
    setLoading(false);
  },
});

Always clear the loading state on both onSuccess and payment_error so the UI never gets stuck after a payment attempt.

Step 6: Test the integration

Before you go live, test the integration on a device that supports Apple Pay. Requirements for testing:

Use your test public key and a test recipient account.
Open your checkout on iOS or macOS.
Make sure your staging domain is enabled for Apple Pay. If you haven’t done this yet, follow Enabling Apple Pay first.

Integration checklist:

The Apple Pay button renders on page load on a supported device.
express_checkout_ready fires with wallets.applePay === true.
Authorizing the Apple Pay sheet triggers onPaymentRequest with payment_method_type: 'card', wallet: 'apple_pay'.
processing_express_checkout_payment fires while the payment is in progress.
onSuccess fires with the payment resource after a successful authorization.
Cancelling the Apple Pay sheet does not emit payment_error.
Calling widget.open() (bank transfer fallback) invokes onPaymentRequest with payment_method_type: 'bank_transfer' and opens the widget.

Optional configurations

Listen to the express_checkout_ready event

After mounting, Express Checkout won’t show buttons until the SDK initializes and checks wallet availability. To animate the element when the button appears, listen to the express_checkout_ready event. Inspect the wallets value to determine which buttons, if any, to display:

// Optional: hide the element until we know if a button will show
const container = document.getElementById("apple-pay-container");
container.style.visibility = "hidden";

window.Fintoc.create({
  // ...
  onEvent: (eventName, metadata) => {
    if (eventName === "express_checkout_ready") {
      if (metadata.wallets.applePay) {
        container.style.visibility = "initial";
      } else {
        // No buttons will show; fall back to bank transfer only
      }
    }
  },
});

Style the button

You can tune the look of the Apple Pay button through the optional fields of expressCheckout.

expressCheckout: {
  container: "apple-pay-container",
  amount: 1000,
  currency: "CLP",

  // Height in pixels. Defaults to 44. Range [40, 100].
  buttonHeight: 52,
  // Border radius in pixels. Defaults to 4. Range [0, 100].
  buttonBorderRadius: 12,
  // Specify the label shown inside the button.
  // Defaults to "plain" for Apple Pay.
  buttonType: { applePay: "buy" },
  // Specify the color scheme of the button.
  // Defaults to "black".
  buttonStyle: { applePay: "white" },
  // Specify the language for the Apple Pay label.
  // Defaults to "es-ES".
  locale: { applePay: "es-MX" },
}

Option	Type	Default	Description
`buttonHeight`	`number` (px)	`44`	Height of the button. Clamped to `[40, 100]`.
`buttonBorderRadius`	`number` (px)	`4`	Border radius of the button. Clamped to `[0, 100]`.
`buttonType.applePay`	`"buy"`, `"pay"`, or `"plain"`	`"plain"`	Label shown inside the Apple Pay button.
`buttonStyle.applePay`	`"black"` or `"white"`	`"black"`	Color scheme of the Apple Pay button.
`locale.applePay`	`"es-ES"` or `"es-MX"`	`"es-ES"`	Language for the Apple Pay button label.

Values outside the allowed range are clamped rather than rejected. For example, buttonHeight: 200 is treated as 100.

The same widget object returned by Fintoc.create exposes the usual widget methods. When expressCheckout is configured, calling widget.open() automatically invokes onPaymentRequest with payment_method_type: 'bank_transfer' before opening the widget, so you don’t need a second initialization.

document
  .getElementById("bank-transfer-button")
  .addEventListener("click", () => widget.open());

Event reference

Express Checkout uses the same onEvent callback as the rest of the widget (widget events reference), plus the events specific to this component:

Event	Payload	When it fires
`express_checkout_ready`	`{ wallets: { applePay?: boolean } }`	Once the SDK finishes initializing. The `wallets` object lists the wallets that were successfully rendered. If empty, none are available, for example on an unsupported browser or an unverified domain.
`processing_express_checkout_payment`	None	After the customer confirms the wallet payment and the SDK is exchanging tokens with your server and the Fintoc backend.
`payment_error`	None	The wallet payment failed at any step: `onPaymentRequest` rejected or timed out, the wallet provider returned an error, or the resulting payment status is not `succeeded`.
`express_checkout_error`	None	An internal error prevented the button from rendering, for example when the SDK fails to load or the container is not found.

Full option reference

Fintoc.create(options)

Parameter	Type	Required	Description
`product`	`"payments"`	Yes	Literal value `"payments"` for Express Checkout.
`publicKey`	`string`	Yes	Your publishable key.
`country`	`"cl"` or `"mx"`	No	Destination country. Defaults to `"cl"`.
`expressCheckout`	`ExpressCheckoutConfig`	Yes	Configuration for the wallet button.
`onPaymentRequest`	`(data) => Promise<{ sessionToken }>`	Yes	Callback that returns a `sessionToken` when the SDK needs one to continue the flow.
`onSuccess`	`(data) => void`	No	Callback that receives the payment resource once the payment reaches `succeeded`.
`onExit`	`(reason?: string) => void`	No	Callback that runs when the widget closes.
`onEvent`	`(eventName, metadata?) => void`	No	Callback that receives every widget event.

ExpressCheckoutConfig

Parameter	Type	Required	Description
`container`	`string`	Yes	`id` of the DOM element where the SDK renders the wallet button.
`amount`	`number`	Yes	Amount to charge, in the currency’s minor unit. For example, CLP has no decimals and MXN uses cents.
`currency`	`string`	Yes	Three-letter ISO 4217 currency code, for example `"CLP"` or `"MXN"`.
`buttonHeight`	`number`	No	Button height in px. Range `[40, 100]`. Default `44`.
`buttonBorderRadius`	`number`	No	Button border radius in px. Range `[0, 100]`. Default `4`.
`buttonType.applePay`	`"buy"`, `"pay"`, or `"plain"`	No	Apple Pay button label. Default `"plain"`.
`buttonStyle.applePay`	`"black"` or `"white"`	No	Apple Pay color scheme. Default `"black"`.
`locale.applePay`	`"es-ES"` or `"es-MX"`	No	Apple Pay button language. Default `"es-ES"`.

Enabling Apple Pay

Apple Pay won’t load on a domain until Fintoc has registered it with Apple. Registration is a prerequisite for both testing and going live. Complete the registration for every domain that will show the button, in both staging and production. Each registered domain must use HTTPS. The process works like this:

Tell Fintoc you want to use Apple Pay. Contact your account manager, customer success contact, or sales contact, and share the domains you plan to integrate.
Host the verification file Fintoc sends you. Fintoc sends you a domain association file. Host it on each domain under the path /.well-known/apple-developer-merchantid-domain-association, so it’s reachable at https://your-domain.com/.well-known/apple-developer-merchantid-domain-association. The file must return 200 OK and be downloadable.
Confirm the file is live. Let Fintoc know once the file is hosted on every domain. Fintoc then registers each domain with Apple.
Test your integration. Once your domains are registered, the Apple Pay button can load, and you can follow the testing steps on a supported device.

If a domain isn’t registered, the Apple Pay button stays hidden and express_checkout_ready reports no available Apple Pay wallet (wallets.applePay is not true). Confirm the domain is enabled before debugging your integration.

Home

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Movements

Accept a one-click payment with Apple Pay

Step 1: Set up your server

Step 2: Set up the Fintoc SDK

Step 3: Create and mount the Express Checkout

Step 4: Handle the onPaymentRequest callback

Step 5: Submit the payment to Fintoc

Handling the loading state during payment processing

Step 6: Test the integration

Optional configurations

Listen to the express_checkout_ready event

Style the button

Event reference

Full option reference

Fintoc.create(options)

ExpressCheckoutConfig

Enabling Apple Pay

See also

​Step 1: Set up your server

​Step 2: Set up the Fintoc SDK

​Step 3: Create and mount the Express Checkout

​Step 4: Handle the onPaymentRequest callback

​Step 5: Submit the payment to Fintoc

​Handling the loading state during payment processing

​Step 6: Test the integration

​Optional configurations

​Listen to the express_checkout_ready event

​Style the button

​Event reference

​Full option reference

​Fintoc.create(options)

​ExpressCheckoutConfig

​Enabling Apple Pay

​See also

Step 1: Set up your server

Step 2: Set up the Fintoc SDK

Step 3: Create and mount the Express Checkout

Step 4: Handle the onPaymentRequest callback

Step 5: Submit the payment to Fintoc

Handling the loading state during payment processing

Step 6: Test the integration

Optional configurations

Listen to the express_checkout_ready event

Style the button

Event reference

Full option reference

Fintoc.create(options)

ExpressCheckoutConfig

Enabling Apple Pay

See also