KPayment

Unified type-safe API integrating Google Pay and Apple Pay, with reactive capability detection, Compose UI payment components, serializable tokens, robust error handling and thread-safe, production-ready state management.

#web
#state-management
#service-sdk
#serialization
#sdk
#compose-ui
#compose-multiplatform
#apple

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Android JVMJVMKotlin/NativeWasmJS

GitHub stars15

Authorskttipay

Dependents0

OSS Health63

LicenseApache License 2.0

Creation date7 months ago

Last activity17 days ago

Latest release0.3.1 (17 days ago)

GitHub repository Wiki page

KPayment - Kotlin Multiplatform Payment Library

One API. Three Platforms. Google Pay & Apple Pay.

Quickstart • Installation • Samples • Documentation •

Overview

A Kotlin Multiplatform payment library with Compose Multiplatform UI components for Google Pay and Apple Pay across Android, iOS, and Web. One API, shared types, reactive availability detection, and platform-native payment buttons.

📱 Platform Support

Platform	Google Pay	Apple Pay	Compose UI
Android	✅	❌	✅
iOS	❌	✅	✅
Web (JS)	✅	✅	✅
WASM	✅	✅	✅

Apple Pay on Web works natively in Safari. On other browsers (Chrome, Firefox, Edge), the Apple Pay JS SDK enables a QR code flow where users scan with their iPhone to pay (iOS 18+).

🚀 Quickstart

// Mobile (Android / iOS)
val manager = rememberMobilePaymentManager(config)
val launcher = rememberNativePaymentLauncher { result ->
    when (result) {
        is PaymentResult.Success -> handleSuccess(result.token)
        is PaymentResult.Error -> handleError(result)
        is PaymentResult.Cancelled -> { /* no action */ }
    }
}
PaymentButton(enabled = isReady, onClick = { launcher.launch("10.00") })

// Web (JS / WASM)
val manager = rememberWebPaymentManager(config)
val applePay = rememberApplePayWebLauncher { result -> /* handle */ }
val googlePay = rememberGooglePayWebLauncher { result -> /* handle */ }
Button(onClick = { applePay.launch("10.00") }) { Text("Apple Pay") }

📦 Installation

Ensure Maven Central is in your repositories, then add dependencies:

# libs.versions.toml
[versions]
kpayment = "0.1.0"

[libraries]
kpayment-core = { module = "com.kttipay:kpayment-core", version.ref = "kpayment" }
kpayment-mobile = { module = "com.kttipay:kpayment-mobile", version.ref = "kpayment" }
kpayment-web = { module = "com.kttipay:kpayment-web", version.ref = "kpayment" }

kotlin {
    sourceSets {
        commonMain.dependencies { implementation(libs.kpayment.core) }
        androidMain.dependencies { implementation(libs.kpayment.mobile) }
        iosMain.dependencies { implementation(libs.kpayment.mobile) }
        jsMain.dependencies { implementation(libs.kpayment.web) }
        wasmJsMain.dependencies { implementation(libs.kpayment.web) }
    }
}

Platform Setup

Android: No additional setup. Google Play Services Wallet is included.

iOS: Add "Apple Pay" capability in Xcode and configure your merchant ID.

Web: For cross-browser Apple Pay, add the JS SDK to your HTML <head>:

<script src="https://applepay.cdn-apple.com/jsapi/1.latest/apple-pay-sdk.js"
        crossorigin="anonymous"></script>

⚙️ Configuration

// Google Pay
val googlePay = GooglePayConfig(
    merchantId = "YOUR_MERCHANT_ID",
    merchantName = "Your Store",
    gateway = GatewayConfig.Stripe(publishableKey = "pk_live_...")
)

See Google Pay gateway configuration for FatZebra, Braintree, Adyen, and other gateways.

// Apple Pay (Mobile)
val applePayMobile = ApplePayMobileConfig(
    merchantId = "merchant.com.yourcompany.app",
    base = ApplePayBaseConfig(merchantName = "Your Store")
)

// Apple Pay (Web)
val applePayWeb = ApplePayWebConfig(
    base = ApplePayBaseConfig(merchantName = "Your Store"),
    merchantValidationEndpoint = "https://example.com/apple-pay/validate",
    baseUrl = "https://example.com",
    domain = "example.com",
    enableJsSdk = true // cross-browser QR code flow (default)
)

🎯 Capability Detection

// Reactive (recommended)
val isReady by manager.observeAvailability(PaymentProvider.GooglePay)
    .collectAsState(initial = false)

Button(enabled = isReady, onClick = { launcher.launch("10.00") }) { Text("Pay") }

// Explicit check
val capabilities = manager.checkCapabilities()
when (capabilities.googlePay) {
    CapabilityStatus.Ready -> { /* show button */ }
    CapabilityStatus.Checking -> { /* loading */ }
    is CapabilityStatus.Error -> { /* handle error */ }
    else -> { /* not available */ }
}

🚨 Error Handling

when (result) {
    is PaymentResult.Success -> sendTokenToBackend(result.token)
    is PaymentResult.Error -> {
        when (result.reason) {
            PaymentErrorReason.NetworkError -> showNetworkError()
            PaymentErrorReason.NotAvailable -> showAlternativePayment()
            PaymentErrorReason.AlreadyInProgress -> { /* disable button via launcher.isProcessing */ }
            else -> showGenericError(result.message)
        }
    }
    is PaymentResult.Cancelled -> { /* no action needed */ }
}

Reason	Suggested Action
`NetworkError`	Check network, retry
`NotAvailable`	Show alternative payment
`AlreadyInProgress`	Disable button via `launcher.isProcessing`
`DeveloperError`	Fix configuration
`Timeout`	Retry after delay
`SignInRequired`	Prompt sign-in

📚 Module Details

KPayment/
├── payment-core/      Shared interfaces, models, config, result types
├── payment-mobile/    Android (Google Pay) + iOS (Apple Pay) implementations
└── payment-web/       Web JS/WASM (Google Pay + Apple Pay) implementations

Each module has its own README with platform-specific details:

payment-core/README.md
payment-mobile/README.md
payment-web/README.md — includes Apple Pay JS SDK button options and cross-browser QR flow

🪵 Logging

KPaymentLogger.enabled = true
KPaymentLogger.callback = object : KPaymentLogCallback {
    override fun onLog(event: LogEvent) { println("[${event.tag}] ${event.message}") }
}

🎨 Samples

sampleMobile — Android + iOS with native payment buttons and capability detection
sampleWeb — Web with Google Pay, Apple Pay JS SDK button, and custom Compose button side-by-side

./gradlew sampleMobile:installDebug              # Android
cd iosApp && pod install && open iosApp.xcworkspace  # iOS
./gradlew sampleWeb:wasmJsBrowserDevelopmentRun   # Web

⭐ Star History

🤝 Contributing

Fork the repo and create a feature branch
Make changes with tests (./gradlew check)
Submit a pull request

Report a bug | Development setup

📄 License

Apache 2.0. See LICENSE.

Built with ❤️ using Kotlin Multiplatform

⭐ Star us on GitHub • 📖 DeepWiki • 🐛 Report Bug