Mobile App Development for Utility Payments: GIS Housing, Billing, SBP Integration

Mobile app development for utility payments is our specialization. Such an app for a management company automates meter readings, charges, and payment collection. Over 5 years, we have delivered more than 15 projects for management companies and aggregators, accumulating integration experience with dozens of billing systems. Imagine: a user opens the app, enters meter readings, sees charges, and pays in three taps. But behind this are dozens of integrations—from GIS Housing to the specific management company's billing, from SBP to push notifications. If the API is not ready or data arrives in "raw" form, deadlines slip. We know how to avoid the pitfalls.

How to Integrate with GIS Housing?

The main challenge is the diversity of data sources. Management companies use different systems: 1C:Housing, Mercury, RCC, or their own billing. Each has its own API scheme—from SOAP services to REST with JWT. Some companies still only provide data in XML with outdated schemas. A data aggregator (e.g., Fintech Hub, Free Utility API, EPS) normalizes information from various sources into a single format—saving up to 80% of integration time.

Practically: if there is no direct contract with the management company, we connect via SMEV or paid intermediaries. The aggregator normalizes data from different companies into a unified format—saving a month of adapter development.

// Request for charges by personal account
struct BillingRequest: Encodable {
    let accountNumber: String
    let period: String // "2025-03"
}

struct BillingResponse: Decodable {
    let services: [UtilityService]
    let totalDebt: Decimal
    let lastPaymentDate: Date?
}

struct UtilityService: Decodable {
    let id: String
    let name: String        // "Cold water supply"
    let amount: Decimal
    let debt: Decimal
    let meterValue: Double? // current reading
}

How is the Meter Reading Problem Solved?

The user enters readings—they go to the billing system via PUT /meters/{meterId}/readings. The billing system only accepts readings during a specific period (e.g., 15th to 25th). Outside that period, an error 403 READINGS_NOT_ACCEPTED_NOW is returned. This must be clearly shown in the UI, not as "Unknown error".

Another nuance: readings must be greater than the previous ones. Client-side validation does not replace server-side, but it saves requests—we immediately block input of a lower value with a hint.

Why SBP is More Convenient for Utilities?

For payments, we use SBP (most convenient for utilities—no commission for individuals), YooKassa, or bank acquiring (if the management company has a direct contract). We create a PaymentOrder with recipient details: Tax ID, KPP, BIC, company account, and payment purpose with the personal account.

When paying multiple services in a batch, each goes as a separate payment because different services have different recipient details. Visually, it's one flow for the user; technically, it is several sequential POST /payments. Cancelling one should not roll back already processed payments.

On Android, Google Pay button via PaymentsClient from com.google.android.gms:play-services-wallet. On iOS—PKPaymentRequest via PassKit. Both require a Merchant ID and an agreement with the acquirer. SBP is 3 times faster to implement than classic acquiring.

Auto-Payments and Debt Notifications

Auto-payments are set up as recurring payments on a schedule. The user specifies the amount and debit day; the system automatically checks charges and initiates payment via SBP or card. If funds are insufficient—a push notification to top up the card. Debt notifications are configured via Firebase Cloud Messaging or APNs. The system sends a push when the balance becomes negative or the payment deadline is approaching.

How is the Development and Testing Process Organized?

We go from auditing sources to deployment. The process includes the following steps:

1. Audit available data sources of the management company (GIS Housing, billing, aggregator).
2. Design a data model that allows adding new providers.
3. Develop screens: personal accounts, meter reading submission, payment.
4. Integrated payment gateway (SBP, acquiring).
5. Configure push notifications and payment history.
6. Test with real data simulating edge cases (double payment, gateway failure).
7. Deploy to App Store and Google Play.
8. Document and train operators.

The billing API response time is usually 200–500 ms, allowing bill payment in 2–3 seconds. Savings on commissions when switching to SBP can be up to 300,000 RUB per year for a management company with a turnover of 15 million RUB.

What is Included in the Work

• Analysis of available data sources of the management company (GIS Housing, billing, aggregator)
• Integration and testing of the payment gateway
• Development of screens for personal accounts, meter readings, batch payment—full utility billing functionality in the mobile app
• Configuration of push notifications and payment history
• Upload to App Store and Google Play (certificates, consents)
• API documentation and operator instructions
• Training for the client's team (2–3 hours)
• 12-month warranty support

Timeline and Milestones

4–6 weeks for MVP with one management company. 8–12 weeks for an app supporting multiple companies via an aggregator, with meter reading submission and batch payment. The cost is calculated individually after requirements analysis.

Order a mobile app development for utility payments—contact us, we will prepare a commercial proposal within a day. Get a consultation: fill out the form on the website or call us.

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.