Built and Operated — Firsthand

From embedded systems to cloud, from planning to operations — hands-on projects delivered.

Technology Stack Overview

Technologies actually used across all projects, organized by layer.

Mobile Apps

FlutterAndroid (Kotlin/Java)iOS (Swift)React Native

Web Frontend

Next.jsReactTypeScriptTailwind CSSShadCN

API Server

Node.js (Express/Fastify)Java Spring FrameworkPHP (Laravel)Python

Database

PostgreSQLMySQL/AuroraOracleMongoDBSQLiteSupabaseFirebase

Cloud / Infrastructure

AWS (EC2/S3/RDS/IoT Core/Lambda/CodePipeline/CloudFront/MediaConvert)DockerNginxCloudflareVercel

Firmware / Embedded

ESP32 (C++/FreeRTOS)BLE 5.0 GATT Protocol DesignMQTTOTASensor Control (I2C/SPI)PID Control Algorithm

AI / Data

Claude/Gemini APIEdge AI (RL/DQN)LSTM Time Series PredictionAI Coding Tools (Cursor IDE)Python Data Analysis

Integrations

PG Payment (In-app/Escrow/Subscription)OCR (Naver/Google)Identity Verification (Account/ID/Face/Micro)SNS Login (Google/Apple/Kakao/Naver)FCM PushSMS/KakaoTalk Notificationi18n (up to 18 languages)

DevOps / Tools

GitGitHub ActionsCI/CD (CodePipeline/CodeDeploy)JiraConfluenceDocker Compose

Analytics / Monitoring

Google Analytics (GA4)Microsoft ClarityCloudflare Web AnalyticsSearch ConsoleConversion Event TrackingHeatmap/Session Recording

Projects

IoT Smart Device — Firmware to Mass Production

Full-stack solo development: firmware, mobile app, API server, admin dashboard, official website, and AI analytics. Crowdfunding sold out.

Role: CTO — Firmware/App/Server/Web/AI

IoTBLEFirmwareFlutterNode.jsNext.jsAWSMQTTAIProduction

Prepaid Top-up Service for Foreigners — 18 Languages

200K MAU. Led Kotlin/Swift to Flutter migration. Custom identity verification (account/ID card/face), OCR, 18-language support.

Role: PL — Led Flutter migration, App/API design

Flutteri18nPGOCRIdentityLarge-scale

Visa & Admin Services for Foreigners — B2C/B2B, 14 Languages

Administrative services for foreigners. Led business/service/web/app planning as PO, full development oversight.

Role: PO — Business/Service/Dev Lead

POi18nGovernmentPaymentB2CB2B

Educational Video Content Platform

AWS media services for video streaming. SNS login, in-app purchase, subscription system.

Role: App/Server/DB

FlutterAWSIn-app PurchaseVideoSubscription

Used Book Trading B2C/C2C Platform

Escrow safe trading system, WebRTC video chat. 10K+ downloads.

Role: App/Web/Server — Planning to Operations

AndroidiOSEscrowWebRTCPlatform

University Textbook C2C Trading Platform

Localized university textbook trading with safe transaction system.

Role: App/Web/Server

AndroidSafe TradeC2C

Calligraphy SNS & Contest Platform

SNS, contests/voting, online exhibitions, point shop — community platform.

Role: App/Web/Server — Planning to Operations

AndroidiOSSNSContestCommunity

Ethereum Wallet App

Ethereum blockchain API integration wallet app.

Role: App Development

AndroidBlockchainEthereum

Blue Light Filter App — 100K+ Downloads, Global

Global release on Google Play. Subscription billing, ad monetization.

Role: App Planning/Dev/Operations

AndroidGlobalSubscription100K+

Game Simulators & Utility Apps

Game simulators, communities, location-based services — 8+ apps developed and operated.

Role: App/Server Planning/Dev/Operations

AndroidGamesCommunityLBS

LG Electronics Android Framework Development

Optimus G Common Framework View System, Input Method, System UI. Jelly Bean upgrade.

Role: Architecture — Framework Dev

Android FrameworkLG ElectronicsSI

Samsung Feature Phone Development — North America

AT&T, TMO, Rogers carriers. SMS, MMS, Call, BT, WAP — full device SW.

Role: SI Dev — Full Device SW

CC++SamsungFeature PhoneOverseas

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