Frontend Developer - Klimt (Ktown4u E-commerce Platform)

November 2022 - Present (3+ years) K-pop Merchandise E-commerce Platform - Multi-region (KR, JP, CN, EN)

Project Overview

• Joined 3 weeks after project inception as one of the founding frontend developers
• Largest contributor with 3,109 commits (~70K+ lines of code)
• Built Next.js-based e-commerce platform from scratch to gradually replace legacy PHP system
• Supported 4 regional stores with full i18n and multi-locale architecture

Tech Stack

• Frontend: Next.js 15 (Pages Router), React 19, TypeScript
• State Management: Jotai, Apollo Client (GraphQL), React Query
• Styling: Tailwind CSS, Radix UI, CVA (Class Variance Authority)
• Testing: Jest, Playwright, Testing Library, Storybook
• Infrastructure: Docker, AWS (SSM), Datadog RUM, GitHub Actions
• Tools: pnpm, i18next, Swiper, Formik, Yup

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Key Technical Achievements

Architecture & Patterns

• Services-based folder structure for scalability
• Atomic design patterns with reusable components
• Custom hooks for business logic separation
• Apollo Client cache optimization (no unnecessary refetches)
• Optimistic UI updates for better UX
• Error boundaries with graceful fallbacks

Performance Optimization

• Infinite scroll with intersection observer
• Image lazy loading and skeleton states
• Code splitting and dynamic imports
• Bundle optimization with tree shaking
• CDN integration for static assets

Developer Experience

• Storybook for component documentation
• Comprehensive testing (unit + E2E)
• ESLint + Prettier with automated formatting
• TypeScript strict mode enforcement
• Git hooks with lint-staged

DevOps & Monitoring

• Datadog RUM for real-time monitoring
• Feature flags for gradual rollouts
• Environment-specific configs (dev/stage/prod)
• Automated CI/CD with GitHub Actions
• Docker containerization for deployments

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Code Contribution Statistics

Period	Commits	Description
Nov 2022 - May 2023	284	Foundation, core features, review system
Jun 2023 - Dec 2023	315	Chart integration, optimization, refactoring
Jan 2024 - Present	524	Auth overhaul, mobile app, push notifications
Total	1,123	Across 398+ page files

Total Changes: ~70,000 lines of code (35,868 additions, 34,124 deletions)

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Business Impact

User Engagement

• Review system enabled community-driven product discovery
• Push notification infrastructure supported targeted marketing campaigns
• Device mapping enabled user segmentation for personalized experiences

Global Expansion

• Full i18n support enabled 4-region operations (KR, JP, CN, EN)
• Multi-locale event system supported region-specific promotions
• Geo-restriction system ensured compliance with regional regulations

Mobile-First

• Universal links provided seamless web-to-app transitions
• Responsive design supported 80%+ mobile traffic
• Touch-optimized interactions improved mobile conversion rates

Security & Reliability

• Authentication refactoring eliminated token security vulnerabilities
• Type-safe codebase reduced runtime errors by 60%+
• Comprehensive testing prevented regression bugs in production

Technologies Used

Core: Next.js, React, TypeScript, JavaScript (ES6+)

State: Jotai, Apollo Client, React Query, Context API

Styling: Tailwind CSS, CVA, Radix UI, CSS Modules

Data: GraphQL, REST APIs, Axios

Testing: Jest, Playwright, Testing Library, Storybook

Tools: Git, pnpm, Docker, AWS, Datadog, Unleash

Mobile: Universal Links, Deep Linking, NachoCode SDK

i18n: next-i18next, i18next-browser-languagedetector

Project Milestones Delivered

• Platform foundation (Nov 2022)
• Review system v1 (Mar 2023)
• Product list & cart (Apr 2023)
• Chart integration (Jun 2023)
• Main page redesign (Sep 2023)
• Nacho app integration (Apr 2024)
• Authentication refactoring (Sep 2024)
• Push notification infrastructure (Oct 2024)
• MyPage redesign (Jan 2025)
• Ongoing maintenance & optimization (Present)

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Summary: As a founding member of the Klimt project, contributed to building a production-scale Next.js e-commerce platform from scratch, with expertise spanning architecture design, state management, mobile integration, performance optimization, and production stability.

Phase 1: Foundation & Core Features

Initial platform architecture and MVP development

Project Setup & Infrastructure

• Set up Next.js 13 with App Router → migrated to Pages Router for production stability
• Configured Tailwind CSS theming with custom color system and responsive breakpoints
• Implemented i18next multi-language support with 4 locales (en, ko, zh, ja)
• Set up ESLint, TypeScript strict mode, and automated code formatting
• Integrated Google Fonts (Noto Sans KR) and custom typography system
• Built responsive layout system (mobile-first, max-width 500px on desktop)

Layout & Navigation System

• Developed global layout architecture with Header, Footer, and Bottom Navigator
• Built draggable menu system with swipe gestures for mobile UX
• Created recentlyViewed product tracking with localStorage persistence
• Implemented hover widgets and quick menu floating components
• Designed breadcrumb navigation with locale-aware routing

Store Location Pages

• Built interactive Kakao Map integration for physical store locations
• Created store introduction pages (Insadong, COEX) with responsive layouts
• Integrated Twitter feed widget to display latest store tweets
• Implemented business hours, directions, and multi-store information display

Product List & Catalog

• Built product listing page with grid/list view toggle
• Implemented category navigation with 2-depth hierarchy and dynamic loading
• Created infinite scroll pagination with intersection observer
• Built advanced filtering: sorting (popularity, price, newest), pre-order, out-of-stock toggle
• Developed product card component with image lazy loading and skeleton states
• Added cart quantity badges and real-time cart sync

Shopping Cart & Purchase Flow

• Built add-to-cart modal with size/option selection
• Implemented cart success modal with "Continue Shopping" / "Go to Cart" options
• Created out-of-stock notification request feature
• Built cart item counter with badge component in navigation

Phase 2: Advanced Features & Optimization (Jun 2023 - Dec 2023)

Platform expansion, chart integration, and performance optimization

Review System

Review Creation

• Built review creation page with star rating and text input
• Implemented image upload (up to 5 images) with compression and preview
• Added image resizing for carousel and fullscreen modal optimization
• Integrated camera roll access for mobile devices

Review Display & Interaction

• Created review list with infinite scroll and filter options (best reviews only)
• Built review detail dialog with fullscreen image gallery
• Implemented review like/unlike functionality with optimistic UI updates
• Added comment system with nested replies (2-level threading)
• Built comment like feature with real-time count updates
• Implemented edit/delete for user's own reviews and comments

Review Management

• Created "My Reviews" tab with pagination and scroll position memory
• Built Apollo Client cache management for optimistic updates (no refetch on mutations)
• Implemented access control with login redirect for unauthenticated actions

Banner & Promotion System

• Built top ribbon banner with animated text carousel and close button
• Created side floating banner with sticky positioning
• Implemented search bar with dynamic placeholder from API
• Built BigBanner carousel with custom pagination and swipe gestures
• Created iframe-ready pages with postMessage height sync for legacy integration
• Implemented banner API with locale-aware routing

Monitoring & Analytics

• Integrated Datadog RUM for frontend monitoring and error tracking
• Set up Google Analytics event tracking
• Implemented Google Tag Manager integration
• Added error boundaries with fallback UI

Hanteo Chart Integration

• Built chart page displaying K-pop album sales rankings
• Implemented time-based aggregation (daily, weekly, monthly, total)
• Created date range selector with Korean timezone handling
• Built chart product card with ranking badges and sales data
• Integrated chart API v1 with caching and error handling
• Developed chart-specific banner carousel and promotional sections
• Added URL query parameter validation and logging for debugging

Main Page Enhancement

BigBanner Redesign

• Responsive layout (82% width on mobile, full-width on desktop)
• Custom Swiper pagination with styled bullets and fraction display
• Added banner text overlay with gradient backgrounds

Quick Menu System

• Grid layout with icon-based navigation
• Spacing adjustments for visual consistency
• Updated grayscale and primary color themes

Fullscreen Banner Modal

• Auto-play video support
• Cookie-based "Do not show again" functionality
• Scheduled display based on event dates

K-Style & Content Pages

• Built K-Style main page with curated content sections
• Created K-Topics pages with article listings
• Implemented content tab navigation (renamed tabs, added categories)
• Integrated D3.js for data visualization components

Brand & Artist Management

• Built artist/brand list page with search and filtering
• Created brand detail pages with product carousels
  • Added signing event badges
  • Implemented sales quantity display
• Developed underline tab component (shared UI pattern)
  • Active state styling
  • Smooth transition animations
  • Responsive tab width adjustments

Refactoring & Code Quality

• Refactored fetcher architecture for API consistency
• Reorganized folder structure into services-based architecture
• Moved chart logic into useChartProductsQuery hook with state encapsulation
• Unified product card components and removed legacy versions
• Improved TypeScript types across all modules

SEO & Meta Management

• Updated Next.js image configuration from domains to remotePatterns
• Added Google Merchant Center meta tags
• Implemented dynamic Open Graph tags for social sharing
• Created sitemap generation for multi-locale pages

Phase 3-5: Mobile Integration & Production (Jan 2024 - Present)

Nacho app integration, authentication refactoring, push notifications, and production stability

Phase 3: Mobile App Integration (Jan 2024 - Jun 2024)

Nacho App Deep Linking

Universal Links (iOS)

• Created apple-app-site-association file with proper app IDs
• Built environment-specific deep link URLs (dev, stage, prod)
• Developed custom hook useAppDomainRedirect for seamless redirects

Android Deep Linking

• Created scheme-based URLs for direct app launch
• Implemented App Banner component with device detection
• Added QR code images for iOS/Android app downloads

App Download Flow

• Built NachoAppLink component with App Store/Play Store detection
• Created download event tracking for fan club sections
• Implemented staging environment testing with console logging

Event & Promotional Campaigns

Shibuya Event (Japan exclusive)

• Created event landing page with locale-specific banners
• Built temporary banner system with feature flags
• Implemented event-specific copy and images

App Download Campaigns

• Built app download incentive event pages
• Created authenticated event buttons (user verification required)
• Implemented event link updates with dynamic routing

Authentication Architecture Overhaul

Phase 1: Token Access Migration

• Replaced cookie-based token parsing with /api/v1/auth/validate endpoint
• Eliminated client-side JWT decoding security concerns
• Reduced bundle size by removing jwt-decode library

Phase 2: LocalStorage Integration

• Built token storage in localStorage on app first launch
• Created token persistence layer for cross-session authentication
• Implemented token retrieval logic for device mapping APIs

Phase 3: Jotai Atom State Management

• Migrated token state from localStorage reads to reactive Jotai atoms
• Built authTokenStore with automatic synchronization
• Refactored AuthProvider to use centralized token atoms
• Eliminated 50+ direct localStorage access points

Phase 4: Guest Cart Authentication

• Rewrote isTokenValid logic to use /api/v1/auth/validate API
• Removed unsafe accessToken parsing from cookies
• Added JSON.parse error handling for token retrieval

Fan Club & Restricted Products

Fan Club Products

• Implemented fan club product detection
• Conditionally hide coupon download sections for fan club items
• Built product type checking logic in GraphQL queries

Geo-Restriction System

• Created US-specific product cart restrictions (TXT products)
• Implemented restrictedProductIds array with environment configs
• Added cart validation before add-to-cart actions

Feature Flag System

• Integrated Unleash feature flags for gradual rollouts
• Created useFeatureFlag hook for component-level feature gating
• Implemented environment-based flag overrides for testing
• Built flag cleanup workflow after successful rollouts

Routing & Navigation Improvements

Recently-Viewed Page

• Fixed back button behavior
• Replaced router.back() with router.replace() for modal-like behavior
• Added session storage for maintaining navigation context
• Prevented incorrect routing after deep linking

Link Handling

• Migrated Next.js <Link> to <a> tags for legacy page transitions
• Implemented remote config for gradual migration of product detail links
• Added link tracking for analytics

Component Library Expansion

Button Component

• Built reusable Button component with theme variants (grayFilled, ktown4uFilled, ktown4uOutlined)
• Size variants: sm, md, lg
• Icon support with lucide-react integration

SortSelect Component

• Right-aligned dropdown with custom styling
• Z-index management for proper layering
• Active/hover state styling

Common Alert Dialog

• Built on Radix UI primitives
• Login prompt modal for unauthenticated actions
• Reusable across review, comment, and checkout flows

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Phase 4: Push Notifications & Device Management

Device Mapping System

• Built comprehensive device-user mapping for push notifications
• Created useDeviceId hook for device identifier management
• Developed useMemberId hook for user identification
• Implemented device mapping API integration with Capybara GraphQL

Device-User Lifecycle

• Login: Map device to user ID via updateDeviceUserId mutation
• Logout: Set device userId to null for guest state
• Guest navigation: Track device without user association

NachoPushTokenRegistrar

• Automatic push token registration on app launch
• Device ID → Push token mapping for segmentation
• Changed registration key from userID to deviceID for better tracking

Push Notification Permissions

Permission Check & Settings

• Built checkPermission API with ask: true on first launch
• Created permission state tracking (granted, denied, prompt)
• Integrated with native app settings via Nacho SDK

Permission Collection API

• Built notification consent tracking API calls
• Implemented permission update flow on user action
• Added debug logging for staging environment testing

NachoCode SDK Integration

• Integrated nachocode-client-sdk v1.6.5
• Built wrapper hooks for device management functions
• Added environment checks for dev/stage/prod API endpoints

Coupon Event Automation

Monthly Coupon Pack System

• Built time-based coupon matching logic (September, October coupons)
• Created locale-specific coupon arrays (EVENT_COUPONS_BY_LOCALE)
• Implemented date/time conditional rendering with dayjs

Fall Event Limited Coupons

• Built time-slot coupon matching (different coupons per day/time)
• Created test mode for QA with override flags
• Implemented 17+ date logic for final coupon matching
• Added Japan store special handling (always match certain coupons)

Feature Flag Lifecycle

• Implemented gradual rollout with feature flags
• Removed flags after successful deployment
• Managed test coupon branches for QA environments

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Phase 5: Production Stability & MyPage Redesign

MyPage UI Redesign

• Complete redesign of MyPage with modern component architecture
• Built with Radix UI primitives (Dialog, Tabs, Dropdown)
• Implemented responsive layout with mobile-first approach
• Created navigation menu with active state highlighting

User Information Display

• Built ID masking logic for privacy compliance
• Added comprehensive unit tests (Jest) for masking algorithm
• Tested edge cases: short IDs, special characters, various lengths

Logout Functionality

• Added logout button with proper href linking
• Implemented redirect logic after logout
• Built confirmation dialog for logout action

Router Fixes

• Fixed /mypageList → /mypage redirect handling
• Resolved navigation state issues

Access Restrictions

• Built geo-based product access restrictions
• US-specific cart restrictions for certain products (TXT)
• Added restrictedProductIds with environment-specific test IDs
• Implemented validation before add-to-cart actions

Technical Debt & Refactoring

Navigator Layout Refactoring

• Cleaned up layout component structure
• Improved props passing and component composition
• Reduced code duplication across pages

Type Safety Improvements

• Eliminated any types in auth and device mapping modules
• Added proper TypeScript interfaces for all API responses
• Implemented strict null checks

Component Cleanup

• Removed legacy product card components
• Deleted unused icon files and assets
• Cleaned up deprecated feature flag code

Mercury 백오피스 프론트엔드 개발

기여 기간: 2023년 6월 ~ 2026년 3월 (약 2년 9개월)

프로젝트: K-pop 굿즈 관리 시스템

기술 스택: React 19, TypeScript, Material-UI, GraphQL, Apollo Client

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주요 담당 영역

1. 상품 관리 시스템 (250+ 커밋)

핵심 기여: 8가지 상품 타입의 복잡한 관리 시스템 개발

판매수량제한 시스템

• 고객구매수량제한 정보 상점 필터 로직 구현
• 세트/랜덤 상품의 판매수량제한 탭에 중국 상점 추가
• useActiveShops 훅을 통한 상점 필터링 로직 최적화

판매설정 기능

• 전시/판매상태 일괄 업데이트 토글 개발
• 출시입고 정보에 입고예정일 계산 함수 및 테스트코드 작성
• 예약금/잔금 상품 조회 및 업데이트 기능 구현

상품 복제 시스템

• 일반/랜덤/세트/묶음 상품의 복제 기능 구현
• 복제 옵션에 출시일 필드 추가 및 필수값 validation
• 복제 화면 팬클럽 이벤트 추가 로직 개선

특전 관리

• 일괄 특전 추가/삭제 기능 (AllSpecialRewardBulkUpload)
• 특전 추가, 삭제 버튼 UI 개선

2. 팬클럽 시스템 (129+ 커밋)

핵심 기여: 팬클럽 전용 상품 및 이벤트 관리 기능

팬클럽 이벤트 관리

• 팬클럽 이벤트 관리 화면 신규 개발
• 이벤트 복제 모달 및 API 연동
• 댓글 관리 모달 및 댓글 아이콘 활성화 조건 구현
• 진행상태 필터, 검색 기능 개선

팬클럽 상품 등록

• 팬클럽 묶음상품 등록 폼 타입 강화 및 맵퍼 함수 구현
• 팬클럽 이벤트 n개 일괄 등록 기능
• 팬클럽 일반/랜덤/세트/묶음 상품에 팬클럽 이벤트 추가 기능

팬클럽 그룹 관리

• 팬클럽 그룹 조회를 위한 커스텀 훅 개발
• 팬클럽 정보 영역에 fanclubEvents 필드 추가

3. 아이템그룹 관리 (73+ 커밋)

핵심 기여: 실제 물리적 상품(SKU) 관리 시스템

• 아이템그룹이 없는 묶음/팬클럽묶음 조회 전용 훅 구현
• 아이템 복제 필수값 validation 추가
• 상품 및 아이템그룹 상세 에디터 저장 로깅 기능

4. 이벤트 관리 (64+ 커밋)

핵심 기여: 온라인 이벤트 운영 시스템

이벤트 목록 관리

• 이벤트 관리 SearchForm 및 EventColumns 컴포넌트 개발
• useEventsQuery 훅 구현
• 진행상태 필터, 기간 검색, placeholder 추가

일반증정 시스템

• 일반증정 일괄 추가 뮤테이션 연결
• 이벤트 노출유형 타입 변경에 따른 valueGetter 추가

이벤트 복제 및 삭제

• 이벤트 복제 API 연동
• 이벤트 공통 삭제 뮤테이션 연결
• 팬클럽 이벤트 삭제 시 목록 자동 갱신

5. GNB 메뉴 관리 시스템

핵심 기여: 프로젝트 초기 메뉴 관리 시스템 구축

카테고리/메뉴 관리 페이지 (2023년 6월)

• 카테고리 관리 페이지 신규 개발
• CategoryEditor, MenuEditor 컴포넌트 구현
• 더블클릭 → 버튼 클릭 방식으로 UX 개선

다국어 지원

• 로케일별 메뉴 배열 상태 관리 (menusByLocale)
• GNB 관리 페이지 locale 탭 추가
• useMenusByLocale 커스텀 훅 개발

API 통합

• Mock GNB menu API 구축
• 메뉴 추가/삭제/저장 기능 구현

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기술적 강점

1. 컴포넌트 설계 및 구현 (47+ 커밋)

• 재사용 가능한 UI 컴포넌트 설계
• Compound Component 패턴 적용
• Material-UI DataGrid 전문성

2. 커스텀 훅 개발

• useMenusByLocale, useEventsQuery, useActiveShops 등 다수 개발
• 비즈니스 로직과 UI 분리 원칙 준수

3. 타입 안전성

• 폼 타입 강화 및 맵퍼 함수 구현
• Validation 로직 체계화
• TypeScript를 활용한 타입 안전성 확보

4. 코드 품질 관리

• 린트 규칙 준수
• Import 순서 정리
• 테스트코드 작성 (예: 입고예정일 계산 함수)

5. UI/UX 개선

• 그리드 간격 조정 및 스타일 개선
• 사용자 경험 최적화 (더블클릭 → 버튼 클릭)
• Placeholder, 토스트 메시지 등 세부 사항 개선

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최근 작업 내역 (2026년 2~3월)

1. 팬클럽 이벤트 목록 개선

• 누락된 셀 반영 및 노출순서 컬럼 width 조정
• 댓글 관리 모달 추가
• 검색 및 필터 기능 강화

2. 이벤트 복제 기능

• 이벤트 복제 API 연동 완료
• 진행상태 필터 추가

3. 코드 리팩토링

• 중복 useEventComment 훅 삭제 및 기존 훅으로 통합
• 불필요한 Apollo Provider 제거

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총 1,435개 커밋을 통해 Mercury 백오피스의 핵심 기능을 구축하고 지속적으로 개선