Stripe Integration in Mobile Apps: A Complete Guide

Stripe Payment Gateway Integration in Mobile Apps

You've embedded card input, but users complain about 3DS failures? Or subscriptions don't charge automatically? Stripe is the most technically mature payment gateway in terms of mobile SDK. It covers not only basic card input but also Apple Pay, Google Pay, 3DS2, Link, and saving payment methods via SetupIntent. Choosing the right flow depends on the task: one-time payment, subscription, card saving without immediate charge — these are different APIs. Our experience shows that most issues arise from selecting the wrong flow or server-side carelessness.

Stripe SDK handles 3DS2 natively, which is confirmed by Stripe's documentation. Proper configuration reduces decline rates by 10–15%.

How Stripe Handles 3DS2

Stripe SDK processes 3DS2 automatically within confirmPayment / PaymentSheet.present. When the bank requires authentication, the SDK opens a native 3DS2 challenge (biometry or OTP) directly in the app — no browser redirect. This is important: 3DS1 redirect via WebView often loses callbacks, and the transaction stalls. If your provider returns requires_action in the PaymentIntent status, that's normal; the Stripe SDK handles the challenge itself. It is through this experience that stable 3DS2 operation is achieved.

Why Choose PaymentSheet Over Custom UI

PaymentSheet speeds up development by 2x compared to custom UI. It includes built-in support for Apple Pay and Google Pay, automatically handles 3DS2 and localization. The custom flow via STPPaymentHandler gives full control but requires more code and testing. If you don't need unique UI elements — go with PaymentSheet.

Step-by-Step Stripe Integration Guide

1. Set up a server endpoint to create PaymentIntent and SetupIntent.
2. Obtain publishable key from Stripe Dashboard.
3. In the mobile app, initialize Stripe SDK with the publishable key.
4. Create PaymentSheet configuration with customer, ephemeralKey, and applePay/googlePay.
5. Call presentWithPaymentIntent and handle the result.
6. Configure webhooks to receive final payment status.
7. Test with Stripe test cards.

How to Choose Between PaymentIntent and SetupIntent

PaymentIntent — for immediate charge. Created on the server, passed to the client via client_secret, the client confirms it. SetupIntent — for saving a card without charge (e.g., during registration, to charge later via API). Similar flow, but without an amount. The main mistake is creating PaymentIntent on the client. secret_key must never enter the app. Only publishable_key is client-side. This way, the secret key never ends up in the client app.

iOS: PaymentSheet and Custom Flow

PaymentSheet (Recommended for Start)

import StripePaymentSheet

var paymentSheet: PaymentSheet?

func preparePaymentSheet(clientSecret: String, customerId: String, ephemeralKeySecret: String) {
    var config = PaymentSheet.Configuration()
    config.merchantDisplayName = "Your Company"
    config.customer = .init(id: customerId, ephemeralKeySecret: ephemeralKeySecret)
    config.applePay = .init(
        merchantId: "merchant.com.yourcompany.app",
        merchantCountryCode: "US"
    )
    config.defaultBillingDetails.address.country = "RU"
    config.allowsDelayedPaymentMethods = true

    paymentSheet = PaymentSheet(
        paymentIntentClientSecret: clientSecret,
        configuration: config
    )
}

@IBAction func checkoutTapped(_ sender: UIButton) {
    paymentSheet?.present(from: self) { [weak self] result in
        switch result {
        case .completed:
            self?.handleSuccess()
        case .failed(let error):
            print("Payment failed: \(error.localizedDescription)")
        case .canceled:
            break
        }
    }
}

Custom Flow with CardField

let cardField = STPPaymentCardTextField()

// Confirming payment
STPPaymentHandler.shared().confirmPayment(
    paymentParams,
    with: self
) { [weak self] status, paymentIntent, error in
    switch status {
    case .succeeded:
        self?.handleSuccess()
    case .failed:
        print("Error: \(error?.localizedDescription ?? "")")
    case .canceled:
        break
    @unknown default:
        break
    }
}

Android: PaymentSheet and CardInputWidget

import com.stripe.android.paymentsheet.PaymentSheet
import com.stripe.android.paymentsheet.PaymentSheetResult

private lateinit var paymentSheet: PaymentSheet

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)

    paymentSheet = PaymentSheet(this) { result ->
        when (result) {
            is PaymentSheetResult.Completed -> handleSuccess()
            is PaymentSheetResult.Failed -> {
                Log.e("Stripe", result.error.message ?: "Unknown error")
            }
            is PaymentSheetResult.Canceled -> {}
        }
    }
}

fun launchPaymentSheet(clientSecret: String, customerId: String, ephemeralKey: String) {
    val config = PaymentSheet.Configuration(
        merchantDisplayName = "Your Company",
        customer = PaymentSheet.CustomerConfiguration(customerId, ephemeralKey),
        googlePay = PaymentSheet.GooglePayConfiguration(
            environment = PaymentSheet.GooglePayConfiguration.Environment.Production,
            countryCode = "RU",
            currencyCode = "RUB"
        ),
        allowsDelayedPaymentMethods = true
    )

    paymentSheet.presentWithPaymentIntent(clientSecret, config)
}

Common Errors and Solutions

Server Side (Minimal Backend)

# FastAPI / Django / Laravel — same logic
stripe.api_key = settings.STRIPE_SECRET_KEY

@app.post("/create-payment-intent")
async def create_payment_intent(amount: int, currency: str = "rub"):
    intent = stripe.PaymentIntent.create(
        amount=amount,  # in cents
        currency=currency,
        automatic_payment_methods={"enabled": True},
    )
    return {"clientSecret": intent.client_secret}

What's Included in the Work

• Implementation of PaymentSheet or custom card flow on iOS and Android
• Server endpoint for creating PaymentIntent / SetupIntent
• Integration of Apple Pay and Google Pay via Stripe
• Webhook setup for final payment status confirmation
• Testing with Stripe test cards

Estimated Timelines

Range: 3–5 days for full integration with Apple Pay, Google Pay, and 3DS2. Basic card flow only — 1–2 days. Average operational cost savings with proper integration is 15–20%. The exact cost is assessed after analyzing your project.

Our engineers hold Stripe certifications (Stripe Certified Developer) and have years of experience in mobile payments. Contact us for an individual assessment of your project. Get a consultation on Stripe integration.

For further study: Stripe and 3D Secure.

Payments in Mobile Apps: In-App Purchase, StoreKit 2, Google Billing, Stripe, RevenueCat

In every monetization project, we balance App Store and Google Play policies, PCI DSS requirements, and purchase verification logic on the backend. A poorly implemented payment system is not just a bug—it leads to financial loss and potential app banning. Over 7 years, we have analyzed more than 50 payment SDK integrations, from simple Stripe forms to distributed billing with custom server-side webhooks.

In-App Purchase: Two Platforms, Two Different APIs

If your app sells digital content or subscriptions, Apple and Google require you to use their payment systems. This is non-negotiable: violating App Store rule 3.1.1 or Google Play Developer Policy results in app removal. Physical goods and offline services are a different story.

StoreKit 2 (iOS 15+)

StoreKit 2 is a complete overhaul of the original StoreKit with async/await API. Product.products(for:), product.purchase(), Transaction.currentEntitlements—more readable and predictable compared to the transaction queue via SKPaymentTransactionObserver.

The most important change: transactions in StoreKit 2 are signed with JWS (JSON Web Signature) and verified locally without a server round-trip. Transaction.verificationResult returns .verified(Transaction) or .unverified(Transaction, VerificationError). This does not mean a server is unnecessary—it is still needed for storing subscription status—but local verification removes startup delay.

StoreKit.AppTransaction verifies the actual app download from the App Store. Required for paid downloads or non-renewing purchases.

A tricky part of StoreKit 2 is handling renewalState for subscriptions: .subscribed, .expired, .inBillingRetryPeriod, .inGracePeriod, .revoked. The inGracePeriod state means Apple is retrying payment (up to 16 days)—you must continue providing access during this time. Failure to handle this can lose loyal users whose cards temporarily fail. Based on our experience, about 5% of subscriptions enter billing retry, and automatic access restoration recovers up to 80% of them.

Google Play Billing Library (v6+)

Google Billing is more complex than StoreKit in terms of scenario handling. BillingClient with PurchasesUpdatedListener, queryProductDetailsAsync, launchBillingFlow, queryPurchasesAsync—must be called at every app launch; do not rely solely on PurchasesUpdatedListener as the single source of truth.

Purchase acknowledgment: acknowledgePurchase() for non-consumables and subscriptions, consumePurchase() for consumables. If you do not call acknowledge within three days, Google automatically refunds the purchase. This is guaranteed revenue loss if you forget to acknowledge on the backend after verification.

ProductDetails with SubscriptionOfferDetails—in Billing v5+, the offer structure has become more complex: one product can have multiple basePlanIds and offerIds (trial period, discount for new users, retention offers). BillingFlowParams.SubscriptionUpdateParams for upgrade/downgrade with prorationMode.

Why Is Server-Side Verification Mandatory?

Never trust only client-side code when unlocking paid content. Client-side verification can be bypassed by modifying the app.

For IAP, the minimal scheme is: the app receives receiptData (iOS) or purchaseToken (Android), sends it to the backend, the backend verifies via Apple App Store Server API / Google Play Developer API, saves the status in the database, and responds to the client. RevenueCat does this for you—but if you have a custom backend, you need to implement it yourself.

Webhooks are more important than they seem. Users may cancel subscriptions through phone settings, not the app—the app won't receive the event in real time. Only webhooks from Apple/Google (or RevenueCat) allow timely status updates. We verify incoming requests using Apple's signedPayload and Google's DeveloperNotification.

How Does RevenueCat Simplify Integration?

Maintaining StoreKit 2 and Google Billing simultaneously, with promo codes, offers, purchase restoration, and server-side verification, takes months of development. RevenueCat handles most of this layer.

RevenueCat is not just a payment SDK. It offers:

• A unified API for iOS and Android (and Stripe for web)
• Server-side verification and subscription status storage
• Webhooks for events (purchase, renewal, cancellation, billing issue)
• Analytics for cohorts, MRR, churn
• A/B testing of offers via Experiments

Purchases.configure(withAPIKey:) at startup, Purchases.shared.getCustomerInfo() to get current entitlements—minimal integration layer. Purchases.shared.purchase(package:) instead of directly calling StoreKit/Billing.

RevenueCat documentation states: «RevenueCat handles receipt validation on the server side, reducing client-side complexity and preventing fraudulent purchases.»

Limitations of RevenueCat: it is paid (free up to $2.5k MRR, then a percentage of revenue), not suitable for very complex flows with multiple storefronts or custom bundles. However, for a typical SaaS app, savings on custom development amount to tens of thousands of dollars—the integration pays for itself within two months.

Stripe in Mobile Apps

Stripe is used for physical goods, services, and B2B payments where IAP is not required by platform policy.

Stripe iOS SDK and Android SDK—PaymentSheet for ready-made payment UI, PaymentSheetFlowController for custom UI with saved cards. Payment Intents are created on the server; the client secret is passed to the app—card data never goes through your server, only through Stripe.

Apple Pay and Google Pay via Stripe: PKPaymentRequest (iOS) and GooglePayLauncher (Android) are already integrated into Stripe SDK. Apple Pay conversion rates are 1.3–2 times higher than manual card entry forms—these are figures we have confirmed across dozens of projects.

Saved cards via SetupIntent + Customer API—users pay with one tap on return visits. Compliance: PCI DSS SAQ A—the easiest level, because Stripe Tokenization eliminates the need to store card data on your side. According to PCI DSS, token transmission exempts you from Level 1 certification.

3DS2 (Strong Customer Authentication) is mandatory for payments in the EU under PSD2. Stripe handles it automatically via PaymentIntent.confirmPayment, but you need to correctly handle the .requiresAction status and return the user to the appropriate screen after authentication.

What Is Included in the Work (Deliverables)

Process and Timeline

We start by clarifying the business model: subscriptions, one-time purchases, consumables, freemium. The architecture depends on this. Testing IAP requires Sandbox accounts (Apple) and License Testers (Google)—this is a separate environment setup.

Apple's Sandbox behaves differently from production: subscriptions renew every 5 minutes instead of monthly, inGracePeriod works differently. It is essential to test scenarios: trial expiration, cancellation, billing retry, refund.

The cost is calculated individually based on the set of tools and complexity of server-side logic. On average, we fit within a budget for a typical integration, but the savings from preventing errors and churn offset this investment within a few months.

Get a consultation for your project—contact us. We will help you choose the optimal payment architecture that passes store reviews and does not break under peak loads.