SkillHub

in-app-purchases

v1.0.0

Implement in-app purchases and subscriptions across iOS, Android, and Flutter with RevenueCat, paywalls, receipt validation, and subscription analytics.

Sourced from ClawHub, Authored by Iván

Installation

Please help me install the skill `in-app-purchases` from SkillHub official store. npx skills add ivangdavila/in-app-purchases

When to Use

User needs to implement in-app purchases, subscriptions, paywalls, or monetization flows. Agent handles native APIs (StoreKit 2, Google Play Billing), cross-platform SDKs (RevenueCat, Adapty, Qonversion), paywall design, server verification, and subscription analytics.

Quick Reference

Topic File
iOS StoreKit 2 storekit.md
Android Billing google-play.md
Flutter packages flutter.md
RevenueCat SDK revenuecat.md
Platform comparison platforms.md
Server verification server.md
Paywall design paywalls.md
Subscription metrics analytics.md
Testing & sandbox testing.md

Core Rules

1. Choose Your Architecture

Approach When to Use Tradeoff
Native only Single platform, full control More code, no cross-platform sync
RevenueCat/Adapty Cross-platform, fast launch 1-2% fee, dependency
Hybrid Native + own backend Full control, more work

2. Platform SDKs (Managed)

Platform Pricing Best For
RevenueCat Free <$2.5k MTR, then 1% Most apps, best docs
Adapty Free <$10k MTR, then 0.6% Cost-conscious, A/B paywalls
Qonversion Free <$10k MTR, then 3% Simple setup
Superwall Paywall-focused Paywall A/B only
Glassfy Free <$10k, then 0.5% Budget option

3. Product Types

Type iOS Android Use Case
Consumable ✅ ✅ Credits, coins, lives
Non-consumable ✅ ✅ Unlock feature forever
Auto-renewable ✅ ✅ Subscriptions
Non-renewing ✅ ❌ Season pass, time-limited

4. Server Verification is Non-Negotiable

Never trust client-side validation alone: - iOS: App Store Server API with JWS verification - Android: Google Play Developer API - RevenueCat: Webhooks + REST API

5. Handle All Transaction States

State Action
Purchased Verify → grant → finish
Pending Wait, show pending UI
Failed Show error, don't grant
Deferred Wait for parental approval
Refunded Revoke immediately
Grace period Limited access, prompt payment
Billing retry Maintain access during retry

6. Subscription Lifecycle Events

Must handle all of these (native or via webhooks): - INITIAL_PURCHASE → grant access - RENEWAL → extend access - CANCELLATION → mark will-expire - EXPIRATION → revoke access - BILLING_ISSUE → prompt to update payment - GRACE_PERIOD → limited access window - PRICE_INCREASE → consent required (iOS) - REFUND → revoke + flag user - UPGRADE/DOWNGRADE → prorate

7. Restore Purchases Always

Required by App Store guidelines: - Prominent restore button - Works for logged-out users - Handles family sharing (iOS) - Cross-device sync

8. Paywall Best Practices

See paywalls.md for detailed patterns: - Show value before price - Anchor pricing (3 options, highlight middle) - Free trial prominent - Social proof if available - A/B test everything

9. Testing Strategy

Environment iOS Android
Dev/Debug StoreKit Config file License testers
Sandbox Sandbox accounts Internal testing
Production Real accounts Production

Sandbox subscription times: - 1 week → 3 minutes - 1 month → 5 minutes - 1 year → 1 hour

10. App Store Guidelines

  • No external payment links (anti-steering)
  • Must use IAP for digital goods
  • Physical goods/services can use Stripe
  • Reader apps have exceptions
  • 15-30% commission applies

Common Traps

  • Testing with real money → use sandbox/test accounts
  • Not finishing transactions → auto-refund (Android 3 days)
  • Hardcoding prices → always fetch from store (regional pricing)
  • Missing transaction observer → lose purchases made outside app
  • No server verification → trivially bypassable
  • Ignoring grace period → users churn when they could recover
  • Poor paywall UX → kills conversion regardless of price
  • Not tracking metrics → can't optimize what you don't measure
  • Forgetting restore button → App Store rejection
  • Not handling family sharing → confused users