Seoul, Korea
Full-stack Node.js engineer and former startup Lead Developer/CTO with 8 years of professional experience and over 20 years of hands-on coding experience. I specialize in 0→1 product development, having founded or joined multiple startups as an early-stage engineering leader. This experience has given me deep expertise in building scalable software architectures from scratch, making foundational technology decisions, and transforming ambiguous ideas into production-ready systems.
I’ve built and scaled products across e-commerce, finance, entertainment, and healthcare domains, with a strong emphasis on code readability, reusability, and long-term maintainability.
I implemented automated frontend and API client generation using Orval, significantly improving type safety and eliminating manual integration overhead. Leveraging Claude Code, I automatically generated REST API test suites and achieved 100% test coverage across endpoints, strengthening reliability and deployment confidence.
I also established comprehensive API documentation standards using Scalar and Swagger, delivering fully defined input/output DTO schemas. Every field is documented with strict types, detailed descriptions, and real-world example values to ensure clarity, consistency, and seamless integration for both internal and external developers.
Beyond backend architecture, I have developed AI-powered products using LLMs such as GPT and Claude, and built RAG pipelines with Llama, Ollama, and AnythingLLM. I also have hands-on experience in blockchain systems, including smart contract development and NFT-based products.
Currently, I am developing predictive AI (ML) platforms for semiconductor manufacturing, serving major enterprise clients such as SK Hynix and Intel.
Web Frontend
React, Next.JS, Vue, Typescript
Backend
Node.JS, Bun, Nest.JS, Prisma, Python, Rust, Kafka
AI
ChatGPT, Claude, Llama, Fine-tuning, RAG
Cloud
AWS, GCP, Azure
Database
PostgreSQL, MySQL, MongoDB
Automation
Puppeteer, Pyautogui
Blockchain
Ethers, ThirdWeb, Solidity
Korean
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English
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Senior Software Engineer & Tech Lead
GaussLabs Inc.
Oct 2024 - Present
Led full-stack design, development, and operations of Panoptes VM as Service team Tech Lead — an AI-powered (ML) Virtual Metrology platform that predicts semiconductor process outcomes using fab sensor, process state, and wafer data, enabling real-time wafer prediction without exhaustive physical metrology. Delivered the web service on Next.js/NestJS for process engineers at enterprise customers including SK Hynix and Intel.
Redesigned and rebuilt the entire frontend and REST API from scratch, achieving significant gains in performance and resource efficiency. Reduced K8s resource consumption by 75% and improved the critical model list query performance by 300x (30,000%) through a combination of caching strategy, dedicated PostgreSQL setup, and application layer data schema modularization. Optimized response times across other core queries by 2–10x. Drove multiple UX improvements — drag-select, keyboard shortcuts, and Kafka/SSE-based web notifications — informed by direct feedback sessions with on-site process engineers.
Introduced Orval to auto-generate frontend React hooks directly from backend API specs, with synchronization automated via GitHub Actions, eliminating manual integration overhead and enforcing end-to-end type safety across service boundaries. Authored an Engineering Rulebook standardizing Swagger documentation across all APIs, mandating strict DTO typing, full descriptions, and real-world example values, significantly reducing communication overhead between internal and external developers.
Co-Founder & CTO
Blackhoods Inc.
Mar 2023 - Jun 2024 · 1 yr 4 mos
Led all technical decisions and full-stack development as Co-Founder & CTO, building and operating two products on Next.js/NestJS/AWS — an AI character platform and a Web3 gaming platform.
Secured seed funding from Kakao Investment, Lotte Ventures, and Alphanonce.
Planned and developed Wame, an AI character platform powered by ChatGPT and Claude 3. Users create and interact with AI-generated fantasy characters, with models fine-tuned to optimize persona consistency and conversation quality, growing the community to 15,000 users.
Developed and operated X2EALL, a Web3 Play-to-Earn games platform serving 300,000 users. Built on a multi-chain architecture across Ethereum-based networks, implementing wallet authentication, NFTs, smart contracts, and third-party airdrop event integrations including Netmarble.
Operated blockchain nodes as a Klaytn Governance Council member and established a partnership as a node operator with Havah.
Technical Director
Kakao Krust Universe
Jun 2022 - Mar 2023 · 10 mos
Built Altverse from scratch (0→1) — a Web3 DID (Decentralized Identity) and marketing campaign platform — owning product naming, architecture design, and technology stack selection. Developed full-stack on Next.js/NestJS/AWS/Vercel/Thirdweb, growing the Discord community to over 10,000 users.
Implemented on-chain DID across Ethereum-based multi-chain networks, built an escrow system using smart contracts, and developed reward-based campaigns utilizing ERC1155 and ERC20 tokens. Automated campaign operations through Twitter API and Discord bot integrations.
Drove cross-chain partnerships including the Chainlink BUILD Program, planning and executing multiple collaborative campaign programs.
Lead Software Developer & Technical Product Owner
Gollala Inc.
Jan 2021 - May 2022 · 1 yr 5 mos
Joined as the first developer of Gollala, a global fashion wholesale e-commerce platform for Dongdaemun apparel. Solo-built the entire commerce website full-stack on Nuxt/Express/MongoDB/GCP, including payment system integration with NICEPay, generating KRW 70M in revenue in the first quarter after launch.
Grew the engineering team from 1 to 20 as Lead Developer and Technical Product Owner (TPO), providing technical guidelines and facilitating cross-functional collaboration across commerce, partner, and purchasing teams. Scaled the platform into a Dongdaemun wholesale sourcing marketplace, reaching approximately KRW 1T in transaction volume.
Co-Founder & CTO
Erunlife Inc.
Apr 2019 - Jan 2021 · 1 yr 10 mos
Co-founded and led all technical development of Smallshim, a leisure curation platform. Full-stack built the user-facing web application, backend systems, and business owner admin site on Nuxt/Express/MongoDB/GCP.
Demonstrated strong early traction, graduating with top honors from Yonsei University's Pre-Startup Package and receiving the Geum-cheon District Mayor Award. The business was closed after COVID-19 eliminated the leisure category from government startup funding programs and froze the investment market.
Software Engineer
Ubiquoss Inc.
Aug 2018 - Apr 2019 · 9 mos
Developed embedded software for a body composition analyzer based on a Texas Instruments custom board. Planned, designed, and built the UI/UX for the touch LCD screen using Python and Kivy. As Kivy was in its early development stages, communicated directly with the original developer via email to resolve technical issues and advance the project.
Researcher (University Research Program)
JW Bioscience
May 2018 - Jul 2018 · 3 mos
Developed UI and image correction modules for medical image processing software using C++ and MFC, through a research program affiliated with Yonsei University.
CEO
T&C Soft
Mar 2018 - Jul 2018 · 5 mos