Yoonsu Lee
I enjoy quickly experimenting with ideas and turning them into product-shaped implementations, and I aim to build services that run reliably in production environments.
Recently, I have been improving workflows that use AI tools and agents to shorten the planning-development-testing loop and automate repetitive tasks.
About
- I quickly validate and implement features from ideas through side projects focused on React and Next.js.
- To improve UI/UX, I measure with Lighthouse, analyze root causes, and iterate on improvements.
- I actively use AI in development. I mainly use Codex and use Claude when needed.
- For AI agent based development, I built and published a CLI for document structure and workflow standardization, and apply Spec-driven development in projects.
- I have been operating Oracle Cloud servers for two years, and deploy/manage side projects in container environments using the open-source PaaS platform Coolify.
Career
Ecount ERP
2024.07 ~ 2025.09
- Server developer responsible for ERP feature development and maintenance
- Debugger-focused issue analysis and fixes in a TypeScript-based in-house framework environment
- Experience handling production errors with a focus on data integrity and loss prevention
- Communication experience from issue definition → implementation → verification in collaboration with planning/QA
- Experience writing RDBMS-based data query/modification queries and integrating them with service logic
Experience
LikeLion
2022.03 ~ 2024.02
- Frontend member and organizer
- After participating as a member of LikeLion at Sahmyook University, I became an organizer based on the knowledge I gained. I led the frontend part and supported session lectures and club activities.
GDSC
2022.03 ~ 2024.02
- Member
- I was an active member of the Google Developer Student Clubs at Sahmyook University, participating in sessions and study groups.
Education
Sahmyook University
2022.03 ~ 2024.02 (Transfer)
- B.S. in Computer Engineering
Projects
A quick overview of recent projects.
Leesfield
AI image/video generation platform
- Adapter-pattern-based image/video generation (currently includes Hugging Face Space adapter)
- Monitoring dashboard
- External API
- Project Type
- Solo Project
- Duration
- 2026-01 ~ 2026-02
- Tech Stack
- Next.js
- TypeScript
- PostgreSQL
lee-spec-kit
CLI to generate a project docs structure for AI-assisted development
- Spec-driven development workflow templates
- Feature-based documentation for simpler progress/review/history tracking
- Agent-friendly context/status summaries and doc structure validation
- Project Type
- Solo Project
- Duration
- 2025-12 ~ 2026-02
- Tech Stack
- Node.js
- TypeScript
Blog
A Next.js blog with multilingual MDX, Studio editor, and GitHub auto-commit
- Author MDX in Studio and auto-commit to GitHub
- Multilingual MDX with OpenAI-powered translation
- Automatic image metadata injection and portfolio PDF generation
- Project Type
- Solo Project
- Duration
- 2025-09 ~ 2026-02
- Tech Stack
- Next.js
- TypeScript
- OpenAI SDK
Leemage
Multi-storage based file and image management platform
- Project-based file upload/management (images, videos, documents, and more)
- Multi-storage adapters (OCI / Cloudflare R2)
- External API and TypeScript SDK
- Project Type
- Solo Project
- Duration
- 2025-05 ~ 2026-01
- Tech Stack
- Next.js
- TypeScript
- PostgreSQL