Payment & Pricing System

Multi-gateway payment system with subscription management and privilege control

Description:

Implemented comprehensive multi-gateway payment system with Stripe (international) and Payple (Korean) integration, featuring subscription management, innovative Day Pass system, and granular privilege management. Achieved 35% improvement in checkout completion and 98%+ payment success rate.

Project Duration:

2022-2023 (Full Stack Engineer at Slid)

Key Technical Achievements:

  • Multi-Gateway Integration: Seamless Stripe and Payple payment processing
  • Subscription Lifecycle: Complete management of subscriptions, upgrades, and downgrades
  • Day Pass Innovation: Flexible short-term access alongside traditional subscriptions
  • Privilege Management: Granular access control based on subscription tiers
  • Performance: 35% checkout completion improvement, 98%+ success rate
  • Multi-Platform: Apple In-App Purchase integration for mobile platforms

Payment Gateway Integration:

  • Stripe Integration: International payments with card processing, webhooks
  • Payple Korean: Local payment methods for Korean market
  • Apple In-App: iOS subscription management with receipt validation
  • Multi-Currency: Support for USD, KRW, and other regional currencies
  • Security: PCI compliance, secure tokenization, fraud prevention

Subscription Management:

  • Tier System: Free, Basic, Premium tiers with feature differentiation
  • Upgrade/Downgrade: Seamless tier transitions with prorated billing
  • Renewal Logic: Automatic renewals with failure handling
  • Grace Periods: Payment failure recovery with user notifications
  • Cancellation: Immediate and end-of-period cancellation options

Technical Implementation:

  • Backend: Node.js with Express, secure webhook handling
  • Payment APIs: Stripe API, Payple SDK, Apple StoreKit
  • Database: PostgreSQL with subscription state management
  • Frontend: React with secure payment forms, real-time updates
  • State Management: Redux for user subscription state

Access Control System:

  • Feature Gating: Granular control over premium features
  • API Limitations: Usage quotas based on subscription tier
  • Real-time Validation: Instant privilege checking for all requests
  • Graceful Degradation: Feature limitations with upgrade prompts
  • Admin Controls: Manual subscription management for support

Day Pass Innovation:

  • Flexible Access: 24-hour premium access for one-time users
  • Pricing Strategy: Lower commitment threshold for user acquisition
  • Technical Implementation: Time-based access control with automatic expiry
  • Conversion Tracking: Day Pass to subscription conversion analytics

Business Impact:

  • Conversion Rate: 35% improvement in checkout completion
  • Payment Success: 98%+ transaction success rate
  • Revenue Growth: 40% increase in subscription revenue
  • Market Expansion: Korean market access through Payple integration
  • User Acquisition: Day Pass system increased trial conversions by 25%

Technical Innovations:

  • Idempotent Operations: Safe retry mechanisms for payment processing
  • Webhook Security: Signature verification and replay attack prevention
  • State Reconciliation: Periodic sync between payment gateways and database
  • Mobile Optimization: Platform-specific payment flows

Skills Demonstrated:

Payment Processing, Subscription Management, API Integration, Security, Database Design, Business Logic, Multi-Platform Development