Google Wallet Loyalty Card Integration for Android: Turnkey

Users want loyalty cards on their phones. Google Wallet is the natural home on Android, installed on 1.5 billion devices. But integrating it is more complex than a simple 'Add to Wallet' button: you need to register an issuer, create a card class, generate JWT, and implement the client API. We have completed over 10 Google Wallet integrations and know all the pitfalls. We offer a turnkey implementation — from console to code, with guaranteed Google review approval in 1-3 days.

For example, for the CoffeeBoom coffee chain, we implemented Google Wallet integration with their bonus program, creating a personalized LoyaltyClass design and automatic point sync via CRM. The project took 3 days for development and 2 days for Google's review. Google Wallet integration ensures users always have their loyalty card handy, boosts engagement by 25–40%, and cuts plastic card production costs by 60–80%. However, stable operation requires proper JWT configuration, error handling, and adherence to Google's rules.

Official documentation: Google Wallet Loyalty API

Integration Steps

Integration proceeds in several stages:

1. Create an issuer account in the Google Pay & Wallet Console.
2. Create a LoyaltyClass — a card template with logo, colors, and fields.
3. Generate a LoyaltyObject for each user server-side.
4. Prepare a JWT for transmission to the client.
5. Implement PayClient.savePasses in the Android app.
6. Handle the add result and update data.

What to Prepare Before Integration?

Before writing code — three steps in the console:

1. Create an Issuer Account
2. Create a LoyaltyClass — card template
3. Obtain service account credentials for server calls

issuerId is the numeric issuer identifier, e.g. 3388000000022142. classId is formed as {issuerId}.{classPostfix}, e.g. 3388000000022142.loyalty_main.

Here are the minimal fields for a LoyaltyClass:

How to Generate a JWT for Each User?

Each user gets a separate LoyaltyObject. We create it server-side and package it into a JWT:

import jwt
import time

loyalty_object = {
    "id": f"3388000000022142.user_{user_id}",
    "classId": "3388000000022142.loyalty_main",
    "state": "ACTIVE",
    "loyaltyPoints": {
        "label": "Points",
        "balance": { "int": user_points }
    },
    "barcode": {
        "type": "QR_CODE",
        "value": f"USER-{user_id}",
        "alternateText": f"USER-{user_id}"
    },
    "textModulesData": [
        {
            "header": "Tier",
            "body": user_tier,
            "id": "tier"
        }
    ]
}

# Create the object via API
service.loyaltyobject().insert(body=loyalty_object).execute()

# Generate JWT for transmission to client
payload = {
    "iss": service_account_email,
    "aud": "google",
    "typ": "savetowallet",
    "iat": int(time.time()),
    "payload": {
        "loyaltyObjects": [{ "id": loyalty_object["id"] }]
    }
}

token = jwt.encode(payload, private_key, algorithm="RS256")

The JWT is passed to the mobile app. JWT lifetime is at most 1 hour, so generate it just before sending.

How to Add a Card in Android via PayClient?

import com.google.android.gms.pay.Pay
import com.google.android.gms.pay.PayApiAvailabilityStatus
import com.google.android.gms.pay.PayClient

private lateinit var walletClient: PayClient

override fun onCreate(savedInstanceState: Bundle?) {
    walletClient = Pay.getClient(this)
    checkWalletAvailability()
}

private fun checkWalletAvailability() {
    walletClient
        .getPayApiAvailabilityStatus(PayClient.RequestType.SAVE_PASSES)
        .addOnSuccessListener { status ->
            if (status == PayApiAvailabilityStatus.AVAILABLE) {
                showAddToWalletButton()
            }
        }
}

private fun saveToWallet(jwt: String) {
    walletClient.savePasses(jwt, this, ADD_TO_GOOGLE_WALLET_REQUEST_CODE)
}

override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
    if (requestCode == ADD_TO_GOOGLE_WALLET_REQUEST_CODE) {
        when (resultCode) {
            RESULT_OK -> handleSuccess()
            RESULT_CANCELED -> handleCanceled()
            PayClient.SavePassesResult.SAVE_ERROR ->
                data?.let { handleError(it.getStringExtra(PayClient.EXTRA_API_ERROR_MESSAGE)) }
        }
    }
}

PayClient.RequestType.SAVE_PASSES checks that Google Wallet is installed and working. On devices without GMS (Huawei), Google Wallet is unavailable — provide a fallback.

How to Update Card Data After Issuance?

To change the points balance — send a PATCH request to the existing object:

patch_body = {
    "loyaltyPoints": {
        "balance": { "int": new_points_value }
    }
}
service.loyaltyobject().patch(
    resourceId=f"3388000000022142.user_{user_id}",
    body=patch_body
).execute()

Google Wallet syncs changes to the device within 2-5 minutes. No push notifications needed — the system updates the card automatically.

Google Wallet or PassKit: Which to Choose?

Google Wallet doesn't require a file archive — everything is through REST API. This speeds up development by 2x and simplifies maintenance. However, on iOS, PassKit works faster offline.

What Our Work Includes?

• Server-side: LoyaltyClass creation, LoyaltyObject and JWT generation, API for data updates
• Client-side: PayClient integration in the Android app, handling add results
• Testing: verification on devices with different Android versions, including Google Wallet emulation
• Documentation: description of all endpoints and developer instructions
• Post-launch support: assistance with Google review, error monitoring

Common Integration Mistakes

• Incorrect classId format: must be {issuerId}.{postfix}, otherwise Google rejects the request.
• Expired JWT: lifetime must not exceed 1 hour, otherwise the client gets an error.
• Missing service account: without correct credentials, the API won't authorize requests.
• Ignoring reviewStatus: while the class is in UNDER_REVIEW status, cards cannot be added to real devices.

Ensure all fields are filled and the server script uses the correct issuerId.

Timeline

2–3 days: LoyaltyClass creation, server-side object and JWT generation, PayClient integration in the Android app. Plus 1–3 days for Google's class review. Pricing is calculated individually. Order a turnkey integration — we'll assess your project and provide a timeline.

Our experience — 5+ years in mobile development, over 10 Google Wallet integrations, hundreds of successfully added cards. We guarantee correct setup on the first try and review approval. Contact us, and we'll find the optimal solution for your business.

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.