FinMont Checkout Flutter SDK #

A standalone Flutter SDK for integrating FinMont payment orchestration into Flutter applications.

The SDK provides a headless payment client with optional prebuilt UI components, 3D Secure authentication, alternative payment methods, digital wallets, and multi-party split payment capabilities.

The SDK is designed around consistent payment concepts and models, including PaymentIntent, PaymentMethod, CheckoutResult, and CheckoutError, with a structured error-handling and payment-processing architecture.

Features #

• Multi-Environment Support Seamlessly switch between FinmontEnvironment.dev, FinmontEnvironment.staging, and FinmontEnvironment.production with automatic API URL resolution.

• Card Payments Client-side card capture, card brand detection, Luhn checksum validation, and secure card tokenization through the FinMont Tokenizer API.

• 3D Secure (3DS) Automatic 3DS challenge detection, full-screen Flutter WebView presentation, return URL callback interception, and secondary authorization handling.

• Multi-Party Split Payments Process payments across multiple cards or payment legs with session caching using cacheReference, live progress streams, and partial failure handling.

• Alternative Payment Methods (APMs) Support for payment methods including SEPA Direct Debit, iDEAL, SOFORT, Bancontact, Klarna, PayPal, Crypto, Vouchers, and UATP airline cards.

• Digital Wallets Native platform integration for Apple Pay and Google Pay.

• Prebuilt UI Widgets Optional customizable UI components including CardFormField, PaymentMethodSelector, SplitBreakdownView, CheckoutResultView, and AddressForm.

• Merchant Branding UI components can be configured using merchant branding and checkout settings.

• Headless Payment Processing Use the core payment client independently from the provided UI components for fully custom checkout experiences.

• Secure Card Handling Card information is tokenized through the FinMont Tokenizer API and is not persisted by the SDK.

Getting Started #

Installation #

Add finmont_checkout to your pubspec.yaml:

dependencies:
  finmont_checkout:
    git:
      url: https://github.com/Finmont-India/finmont_checkout.git

If the package is published on pub.flutter-io.cn, you can use:

dependencies:
  finmont_checkout: ^0.1.0

Then run:

flutter pub get

Quick Start #

Initialize FinmontCheckout with your FinMont API authentication token:

import 'package:finmont_checkout/finmont_checkout.dart';

final checkout = FinmontCheckout(
  apiKey: 'your_api_jwt_bearer_token',
  environment: FinmontEnvironment.dev,
);

Usage Examples #

1. Simple Card Checkout #

Create a payment intent and process a card payment:

final intent = PaymentIntent(
  amount: const Amount(
    currency: 'EUR',
    value: 4999,
  ), // €49.99 in minor units
  order: const Order(
    reference: 'ORD-1001',
  ),
  shopper: const Shopper(
    name: 'Jane Doe',
    email: 'jane@example.com',
  ),
);

final card = const CardDetails(
  number: '4111111111111111',
  expiryMonth: '12',
  expiryYear: '28',
  cvc: '123',
  holderName: 'Jane Doe',
);

// Process payment.
// The SDK tokenizes the card and submits the payment
// through the FinMont payment orchestration layer.
final authorized = await checkout.processCardPayment(
  intent: intent,
  card: card,
);

// Handle 3DS if required.
if (authorized.is3D) {
  final threeDSResult = await ThreeDSWebView.show(
    context,
    challengeUrl: authorized.response3Ds!.url!,
    receiptReference: authorized.receiptReference!,
  );

  if (threeDSResult != null && threeDSResult.isSuccess) {
    final finalResult = await checkout.confirmThreeDS(
      receiptReference: authorized.receiptReference!,
      previousIntent: authorized,
    );

    print('Payment confirmed: ${finalResult.receiptReference}');
  }
} else {
  print('Payment authorized: ${authorized.receiptReference}');
}

2. Using the Prebuilt Card Form Widget #

The SDK provides a customizable card form for collecting and validating card information:

final cardFormKey = GlobalKey<CardFormFieldState>();

CardFormField(
  key: cardFormKey,
  currency: 'EUR',
  onCardChanged: (cardDetails) {
    print('Card valid: ${cardDetails?.last4}');
  },
);

ElevatedButton(
  onPressed: () {
    if (cardFormKey.currentState?.validate() ?? false) {
      final card = cardFormKey.currentState!.getCardDetails()!;

      // Execute payment...