Flutter SDK

The hundredpay Flutter package lets you accept crypto payments in iOS and Android apps with a single method call. It opens the 100Pay Checkout UI inside your app using a native webview.

Supports Android and iOS
Minimal setup — just pass customer and billing info
Built on webview_flutter under the hood

Package: pub.dev/packages/hundredpay

Getting Started

Create a 100Pay Account

Add the Dependency

In your pubspec.yaml:


dependencies:
  hundredpay: ^latest

Then run:


flutter pub get

Android Compatibility

Your minSdkVersion must be 19 or higher. Open android/app/build.gradle and update:


android {
  defaultConfig {
    applicationId "com.yourapp.id"
    minSdkVersion 19        // Must be 19 or higher
    targetSdkVersion flutter.targetSdkVersion
    versionCode flutterVersionCode.toInteger()
    versionName flutterVersionVersion
  }
}

Make a Payment

Import the package and call HundredPay.makePayment():


import 'package:hundredpay/hundredpay.dart';
 
// Generate a unique reference ID per transaction
final String refId = DateTime.now().millisecondsSinceEpoch.toString();
 
await HundredPay.makePayment(
  customerEmail: "[email protected]",
  customerPhoneNumber: "0800000000",
  customerName: "Jane Doe",
  customerUserId: "user_123",         // Your internal user ID
  amount: "49.99",
  userId: "12345",                    // Your 100Pay user/app ID
  refId: refId,                       // Unique per transaction
  description: "Monthly subscription",
  apiKey: "LIVE;PK;your_public_key",  // From Developer Settings
  currency: "NGN",                    // e.g. "USD", "NGN", "GHS"
  country: "NG",                      // ISO country code
  chargeSource: "api",
  callBackUrl: "https://yourapp.com/payment/callback",
  onError: (error) {
    print("Payment error: $error");
  },
  onComplete: ({ completed }) {
    if (completed) {
      print("Payment completed successfully!");
      // Verify payment on your backend using the refId
    }
  },
  context: context,
);

Parameters

Parameter	Type	Required	Description
`customerEmail`	`String`	✅	Customer’s email address
`customerPhoneNumber`	`String`	✅	Customer’s phone number
`customerName`	`String`	✅	Customer’s display name
`customerUserId`	`String`	✅	Your app’s internal user ID
`amount`	`String`	✅	Payment amount as a string (e.g. `"49.99"`)
`userId`	`String`	✅	Your 100Pay user/app identifier
`refId`	`String`	✅	Unique transaction reference — generate a new one per payment
`description`	`String`	✅	Short description of the payment
`apiKey`	`String`	✅	Your Public API Key from the Developer Settings — format: `"LIVE;PK;..."`
`currency`	`String`	✅	Currency code (e.g. `"NGN"`, `"USD"`, `"GHS"`)
`country`	`String`	✅	ISO 3166-1 alpha-2 country code (e.g. `"NG"`, `"US"`)
`chargeSource`	`String`	✅	Always `"api"` for SDK-initiated payments
`callBackUrl`	`String`	✅	URL invoked after payment completes
`onError`	`Function(error)`	✅	Called if an error occurs during payment
`onComplete`	`Function({completed})`	✅	Called on completion — `completed: true` means the user finished the flow
`context`	`BuildContext`	✅	Flutter `BuildContext` from the calling widget

onComplete fires when the checkout UI closes — not necessarily when the payment is confirmed. Always verify the payment on your server using the refId before fulfilling orders or granting access.

API Key Format

Your API key includes a mode prefix. It looks like:


LIVE;PK;eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9...

LIVE — production mode (TEST for sandbox)
PK — public key type (SK for secret key — never use server-side keys here)
The token after the second ; is the actual key payload

Copy the full string from your Developer Settings .

After Payment: Verify on Your Server

The onComplete callback is client-side only. Use the refId you passed in to verify the payment via your backend:


onComplete: ({ completed }) async {
  if (completed) {
    final result = await http.post(
      Uri.parse("https://yourapp.com/api/verify-payment"),
      body: jsonEncode({ "refId": refId }),
      headers: { "Content-Type": "application/json" },
    );
 
    final data = jsonDecode(result.body);
    if (data["success"] == true) {
      // Unlock feature / navigate to success screen
    }
  }
},

See Verify Payments for the server-side verification guide using the 100pay.js SDK.

Dependencies

The hundredpay package relies on:

Package	Purpose
`webview_flutter`	Renders the checkout UI inside a native webview
`http`	HTTP client for API communication
`flutter_spinkit`	Loading indicators
`plugin_platform_interface`	Flutter plugin interface

Next Steps

Verify Payments — confirm payments server-side after checkout
Pay Checkout JS — web equivalent of this SDK
100pay.js — server-side Node.js SDK for transfers, subaccounts, and more