Available for remote contract work: 13-year full-stack dev (billing, admin, payments)

I'm Sangyoon Lee, a full-stack developer in Seoul with 13 years of experience, and I'm available for remote contract work starting now.

What I build and fix

• Admin dashboards and back-office tools (members, orders, settlement, permissions, change history)
• Billing, settlement and payment integrations (PG, recurring payments, kiosk/card terminals)
• Backends for web and mobile apps, plus Flutter apps shipped to iOS and Android
• Stack: Laravel and CodeIgniter, Spring Boot, Node.js/TypeScript, React, Vue, MySQL/PostgreSQL/Redis, AWS, Docker

Things you can check

• I replaced a production app's backend (serverless to Spring Boot WebFlux) without forcing a user app update.
• I built a multi-channel settlement reconciliation engine (Java 17, idempotent reprocessing, rollback).
• I shipped three new services in two months as the only developer, all on schedule.

How I work
Remote only. Scope and acceptance criteria are agreed in a document before I start, progress is written up every week, and I reply within 24 hours, weekends included. Calls are fine; I keep decisions in writing so nothing gets lost.

If you have a backend, admin or integration task that keeps slipping, send me a short description and I'll reply with a plan.

Portfolio: https://cv.namubase.com