Interswitch Payment Gateway SDK for Flutter #

The Interswitch Payment Gateway (IPG) SDK for Flutter provides a seamless way to integrate secure payment processing into your mobile applications. Built on top of the robust Interswitch Web Checkout, this SDK simplifies the integration process using a WebView-based redirect flow.

Official Documentation

Features #

• Official Integration: Follows Interswitch Web Redirect standards.
• Cross-Platform: Full support for both iOS and Android.
• Pure Dart: No native dependencies - simple integration without platform-specific setup.
• Multiple Payment Methods: Card, Bank Transfer, USSD, QR Code, OPay, and Wallets.
• Built-in Error Handling: Custom WebpayException for network and WebView errors.

Installation #

Add the package to your pubspec.yaml:

dependencies:
  interswitch_payment_gateway: ^0.0.1

OR

Run this command

flutter pub add interswitch_payment_gateway

Then run:

flutter pub get

Note: This package requires webview_flutter which is included as a dependency. No additional setup needed.

Quick Start #

The following example demonstrates a basic payment implementation.

import 'package:flutter/material.dart';
import 'package:interswitch_payment_gateway/interswitch_payment_gateway.dart';

class PaymentScreen extends StatelessWidget {
  // Replace with your actual Interswitch credentials
  // These are test credentials for demonstration
  final webpay = WebpayClient(
    merchantCode: '<merchant-code>',        // Test merchant code
    payItemId: '<pay-item-id>',          // Test pay item ID
    redirectUrl: '<redirect-url>',
    mode: EnvironmentMode.test,
  );

  Future<void> makePayment(BuildContext context) async {

    try {
      final result = await webpay.checkout(
        context: context,
        amount: 100000, // Amount in Kobo (e.g., 100000 = ₦1,000.00)
        txnRef: '<transaction-reference>',
        custEmail: '<customer-email>',
      );

      if (result == null) {
        // User cancelled the payment
        return;
      }

      if (result['resp'] == '00') {
        // Payment successful - verify on your backend
        print('Success! Ref: ${result['txnref']}');
      } else {
        // Payment failed
        print('Failed: ${result['desc']}');
      }
    } on WebpayException catch (e) {
      // Technical error (network, WebView, etc.)
      print('Error: ${e.message}');
    }
  }

  @override
  Widget build(BuildContext context) {
    return ElevatedButton(
      onPressed: () => makePayment(context),
      child: const Text('Pay Now'),
    );
  }
}

Advanced Usage #

With Customer Information #

Pre-fill customer details to streamline the checkout experience.

final webpay = WebpayClient(
  merchantCode: 'YOUR_MERCHANT_CODE',
  payItemId: 'YOUR_PAY_ITEM_ID',
  redirectUrl: 'https://your-domain.com/callback',
  mode: EnvironmentMode.live,
  // Default customer info (can be overridden per transaction)
  custName: 'John Doe',
  custEmail: 'john@example.com',
  custId: 'CUST_12345',
  payItemName: 'Premium Subscription',
);

API Reference: WebpayClient Constructor #

API Reference: checkout() Method #

Response Handling #

Payment Response Fields #

Result Scenarios #

Common Response Codes #

For a complete list, see Response Codes.

Transaction Verification #

Important: Always verify transactions on your backend server using Interswitch's Transaction Status API. The client-side response should not be solely relied upon for confirming payment status.

Test Cards #

For testing in sandbox mode, use test cards from Interswitch: Test Cards Documentation

Example #

See the example directory for a complete working implementation.

Contributing #

We welcome contributions! Please submit pull requests or open issues on the GitHub repository.

License #

This project is licensed under the MIT License - see the LICENSE file for details.

Built for the Flutter community