Senior Backend Engineer - Go, Node.js/TypeScript, PHP/Laravel
- Location
- South Korea
- Rate, USD
- $60 / hour
- Work schedule
- Contract, Part Time,
- Language skills
- English, Korean
- Available for Hire
- Yes
About me
Backend engineer with 9 years of experience spanning full-stack web services (PHP/Laravel, Node.js/TypeScript, React/Next.js) and high-throughput real-time systems in Go – most recently a production order management system running 100+ concurrent trading strategies. Comfortable owning a service end to end, from API and data model to frontend.
I use AI-assisted development (Claude Code) as a day-to-day pair-programming tool across the whole dev loop – planning, writing and reviewing code, and triaging failures from logs – while still treating AI output as untrusted input that gets reviewed before anything ships. Comfortable with milestone-based delivery and async communication across time zones.
Professional area
Education
- Feb 2013 - Jun 2016 Associate Degree, Computer & Electronic Engineering @ Myongji College
- Feb 2010 - Feb 2013 Electronics @ Yongsan Technical High School
Experience
- Aug 2025 - May 2026 Senior Engineer, Quantitative Engineer @ OneBullEx
– Owned both the backend and the React/TypeScript ops dashboard for a multi-strategy algorithmic trading system; applied an AI-native (Claude Code) development methodology to build and operate a complex trading system as a single engineer.
– Built a real-time operations dashboard (Go/fasthttp backend, React/TypeScript frontend) showing live uPnL, positions, and order history via a WebSocket hub, plus a 1-minute snapshot worker reconciling exchange REST data into a NAV/PnL pipeline; infra metrics via VictoriaMetrics + Grafana (15+ custom metrics).
– Developed a multi-strategy OMS execution engine in Go handling 100+ concurrent trading signals – queueing/throttling/retry against exchange rate limits, FSM-based execution from signal to fill, and safeguards against duplicate/rapid-fire signals; achieved P99 200ms order processing even against exchanges without WebSocket support.
– Designed an AI-native development workflow for long-running complex systems: layered context documents, Claude Code hooks enforcing project rules, an AI code-review loop, and MCP/Skills-based code search to keep AI output consistent with agreed specs.- May 2024 - Jul 2025 IT Director @ JJHOLDINGS Inc.
– Sole owner of infrastructure and internal systems (4-5 systems: CRM, web, app, internal tools) used by roughly 30-50 people across 4 departments.
– Led parallel new-CRM development and legacy-CRM maintenance – prioritized via stakeholder interviews and ran the full cycle from planning through deployment and support.
– Full-stack development of new internal web services end to end (requirements, UI/UX, frontend/backend, deployment, operations).
– Owned company-wide infrastructure and data governance – servers, network, accounts, security, backups; unified previously siloed departmental data.
– Managed and maintained the company’s mobile app.- Jul 2023 - Apr 2024 CEO / Freelance Developer @ SEA (Baada)
– Independently won, developed, and delivered freelance projects (Laravel/React) across 4 new builds and 2 maintenance contracts over about 10 months, owning the full lifecycle – client meetings, quoting, scheduling, development, QA, deployment, and operations – across multiple concurrent clients.
– Completed a 2-month short-term frontend placement at an SI firm, ramping up quickly on an existing codebase, domain, and team culture to deliver results immediately.- Jul 2022 - Jul 2023 Backend Team Lead (Playing Lead) @ Coworkernet
– Joined as dev-team lead transitioning the org from SI-agency work to an in-house team, and reorganized how the team worked – process, tech stack, and hiring.
– Led the migration from legacy HTML/jQuery to React, defining component architecture, state-management patterns, and build-environment standards; onboarded the team onto React as the new default stack.
– Owned junior-developer hiring, onboarding, and incubation – from interviews to real project deployment, via code review and pair programming.
– Introduced Slack/Notion and defined collaboration processes – channel structure, notification rules, doc templates, and workspace structure for async communication.
– Backend development of B2B/B2C SaaS APIs (Laravel) – RESTful APIs, DB schema, auth/permissions, and external integrations.- Jul 2020 - Jun 2022 Project Manager @ Fifteen H
– Dev-background PM overseeing multiple web/app projects as the communication hub between planning, design, and development.
– Managed cross-department communication and project delivery – requirements gathering, scheduling, issue tracking, and translating between technical constraints and business requirements (including with the design team).
– Managed iOS app releases and native integrations – APNs push, StoreKit auto-renewing subscriptions (IAP) with receipt validation and restore, and App Store review compliance, while keeping the existing payment structure intact through review.- Jun 2017 - Jun 2020 Application Software Developer @ Sunwoon E&G
– Sole designer/developer of AutoCAD workflow-automation programs and libraries at a surveying/engineering firm.
– Built and patented a 3D-LiDAR-based transmission-line sag-detection library – isolating candidate wires from large-scale 3D point clouds and auto-computing sag curves via curve fitting; adopted into the company’s standard workflow and recognized for technical originality (registered patent).
– Developed a unified AutoLISP library-management program (platform-level design).
