Event App Development: Ticketing, QR Entry, Scheduling & Networking

Organizers of large festivals face a dilemma: before the event, maximize ticket sales; during the event, provide navigation, networking, and live updates for thousands of participants. We create event apps that work in both modes without compromise. Our experience includes projects for conferences, music festivals, and sports events—each with its own specificity.

An event app lives in two modes: before the event (poster, ticket purchase, anticipation) and during (schedule, navigation, networking). Technically, these are different sets of requirements, and a common mistake is treating them the same. Before the event, purchase conversion is critical. During the event, it's about offline-first performance, speed, and real-time schedule updates.

Tickets

The event screen: description, speakers, program, remaining seats, "Buy" button. Ticket type selection (General, VIP, Online) → cart → checkout. For limited-capacity events, we implement a real-time counter via WebSocket or polling. If seats run out a second before purchase, we return 409 Conflict with a clear message.

Season passes or multi-day festivals require a single order covering multiple dates. Group purchase: the user buys 4 tickets, enters each participant's email—each receives their own QR.

The payment flow is critical. We integrate Apple Pay and Google Pay to minimize friction. Saved cards for repeat purchases. Using Stripe, Checkout.com, or a regional acquirer, conversion increases by 15–20%.

Why Real-Time Schedule Synchronization Matters

At a festival, the schedule changes every 10 minutes: a speaker falls ill, a session is moved. If the app shows outdated data, participants lose trust. WebSocket updates and push notifications solve this problem. On the client, we treat scheduleSessions as an Observable/Stream—when data changes, the UI redraws without a full reload.

QR Entry at Check-In

QR codes for tickets: JWTs containing ticketId, eventId, userId, exp (expiration), signed with a server key. On scanning at entry: signature verification → exp check → mark ticket as used (redemption flag in DB).

Protection against screenshot sharing: animated QR codes that refresh every 30 seconds with a new iat—a standard for large festivals. Offline: we accept the last loaded code with offline verification using a cache of used tickets on the volunteer's device.

The volunteer scanner app is either a separate build target or a separate app. Scanning uses AVFoundation / ML Kit. Sound and vibration feedback for successful/erroneous scans—crucial in a noisy crowd.

Schedule and Program

Multi-room schedule: horizontal time axis, vertical rooms/stages. We implement it with UICollectionViewCompositionalLayout or a custom Canvas. Overlapping sessions are displayed in parallel.

Personalized schedule: the user marks "Want to attend"—sessions are added to a personal program. Conflicts ("at 15:00 you have two events simultaneously") trigger a warning.

Real-time changes: a speaker falls ill, a session is moved. WebSocket schedule updates, push notifications to subscribed users. On the client: scheduleSessions as an Observable/Stream—on update, the UI redraws without reload.

Offline: schedule is cached on first load. At a festival, up to a third of attendees have no internet—the app must work. We use Core Data / Room / Isar with background sync when connectivity resumes.

How We Ensure Offline Operation at a Festival

Offline mode is a basic need for event apps. We cache the schedule, venue map, and QR tickets on the device. Synchronization happens in the background: when network appears, data updates, and conflict resolution uses last-write-wins. For networking, we use Bluetooth proximity, which requires no internet.

Networking

Participant profile: name, company, role, photo, links. Visibility is configurable (everyone / by request / hidden).

"Find people nearby" using Bluetooth proximity via CoreBluetooth (iOS) / Nearby Connections API (Android). Proximity radius ~10 meters. When another participant with networking enabled is detected, a banner pops up: "Nearby: Ivan Petrov, CTO at Acme Corp."

Business card exchange via NFC (NFCNDEFReaderSession iOS / NfcAdapter Android)—participants tap phones to exchange profiles. QR business card as a fallback.

Chat: private messages between participants, group channels by topic. We use Stream Chat or SendBird—ready SDKs with push notifications.

Participant Interactivity

Live Q&A: participants ask questions via the app, upvote others' questions. On the organizer screen, a real-time list sorted by rating. WebSocket synchronizes votes.

Polls: the speaker launches a poll → participants answer → results shown in real-time on a slide. We use ready solutions (Mentimeter API) or custom implementation via WebSocket.

A Case Study: Large Music Festival

On a recent project for a major music festival with 50,000 attendees, we replaced a static PDF schedule with a real-time WebSocket-driven app. The previous system required organizers to manually update PDFs and push notifications; announcement delays reached up to 10 minutes. Our solution integrated the scheduling backend directly with the app via WebSockets, allowing updates to propagate in under 2 seconds. The personalized schedule feature was used by 78% of attendees, and the offline mode ensured reliable access even in areas with poor network coverage. Check-in time dropped from 30 seconds per person to 5 seconds thanks to animated QR codes and offline verification.

Tech Stack and Platform Comparison

React Native is a popular choice for event apps: cross-platform, fast start, sufficient performance for schedules and chats. We use Zustand or Redux Toolkit for schedule state. react-native-vision-camera for QR scanning.

Flutter is similar but offers higher animation performance. Native Swift + Kotlin is preferred when Bluetooth proximity, NFC business card exchange, and maximum schedule performance are needed.

What's Included in Event App Development

Our Process

Poster and checkout design → QR system and volunteer app → schedule with offline support → networking → interactivity → testing at a real event (pilot run) → publishing.

Timeline Estimates

MVP (poster, ticket purchase, QR entry, schedule): 4–7 weeks. Full-featured event app with networking, live Q&A, Bluetooth proximity, and multi-platform scanner: 2–4 months. Project cost is determined after requirements analysis.

We have been in the market for over 5 years and have delivered 15+ event apps for conferences, festivals, and sports events. Order your event app development today—we'll propose the optimal solution. Contact us for a preliminary assessment of your project.

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.