Oh Hyunji — Full-stack Developer
I design and build polished business websites, admin tools, and AI-ready workflows that are practical to launch and maintain.
Business websites, dashboards, and operational tools
Reliable delivery with deployment, performance, and handoff in scope
Next.js, Nest.js, AWS, and practical AI workflows
Portfolio and freelance introduction in one place
This site brings together selected projects, delivery outcomes, and the kind of freelance work I take on.
My work is centered on Next.js, Nest.js, AWS, admin systems, and practical AI-enabled automation for real operations.
If you need a business website, dashboard, internal tool, or a scoped AI-assisted workflow — this is the single overview.
helloqu@naver.com
What I deliver
Focused on scoped work that needs both product thinking and reliable execution.
01
Business websites & product surfaces
Launch or refresh branded websites, landing pages, and user-facing flows with SEO, analytics, and responsive UI built in.
02
Admin dashboards & workflow tools
Build operations-facing systems that reduce manual work and make day-to-day processes easier to manage.
03
AI-assisted features & automation
Add practical AI where it helps — support workflows, document handling, internal assistants, or retrieval-based experiences.
Company sites with lead capture, admin dashboards, internal tools, operational workflows, and selective AI-enabled features.
Impact Metrics
Quantified outcomes from delivery, optimization, operations, and AI-enabled automation.
40%
Faster defect resolution
Improved triage, diagnostics, and test coverage, with AI-assisted automation.
4
Product surfaces delivered
Kiosk, mobile, web, and admin releases aligned to one roadmap.
4+ yrs
End-to-end delivery
From platform APIs to production-grade UI.
Selected Projects
Ordered from the most recent work, highlighting implementation scope and operational thinking.
Festival Cardnews Prompt
A content operations platform that turns festival data into AI-generated cardnews, Canva assets, and scheduled Instagram posts
INSPIRE Workforce Management System
An event operations dashboard for staffing visibility, role-based evaluations, and administrator updates
NexusLuxor
A Firebase-based commerce back office and kiosk integration system covering orders, payments, reconciliation, and notifications
CookieRun Waiting System
A NestJS and Redis-based real-time queueing platform for registration, calling, entry handling, notifications, and operations metrics
Kiosk Payment Integration System
A production-grade payment authentication and cancellation flow connecting on-site terminals with kiosk UI
BusinessPlus CRM
A corporate site renewal aligned with the brand positioning of a B2B IT consulting firm
Hanleeon Patent Consulting
A Cafe24-based website renewal focused on service clarity and online consultation flow for a patent law office
Account & Profile
Unified account, security, and scanner settings for user profile management
Report Management
A report operations screen with filtering, lookup, and export workflows
Inno3Dental Dashboard
An administrative dashboard combining reports, storage usage, and core operational metrics
Inno3Dental Chat
A partner-network collaboration platform with Redis-backed sessions and real-time group messaging
Case Studies
Selected engagements with explicit problem definition, solution, outcomes, and AI integration.
Kiosk Payment Integration
Problem Payment flows were inconsistent across devices and connection states.
Solution Delivered a C#/.NET HTTP plugin, hardened JS↔C# bindings, and implemented fallback handling.
Result Stabilized /Auth and /Cancel flows with resilient device orchestration.
QR/Barcode Scanner Connectivity
Problem Scanner data loss and inconsistent parsing in kiosk environments.
Solution Implemented RS232 parsing, validation, and asynchronous UI synchronization.
Result Improved scan accuracy and response feedback consistency.
Real-time Platform Features
Problem High-traffic collaboration required reliable real-time messaging.
Solution Implemented WebSocket messaging with Bull Queue and Redis session sharing.
Result Sustained 1:N group chat with stable session continuity.
Waiting System Modernization
Problem Peak-time traffic caused inconsistent ordering and operational recovery issues.
Solution Implemented Redis atomicity with DB synchronization, session scopes, and fallback recovery flows.
Result Delivered consistent sequencing, duplicate-prevention, and reliable recovery under load.
Settlement Statement Site
Problem Manual settlement documentation created operational delays and inconsistencies.
Solution Built an AI-assisted internal settlement site with standardized workflows and deployment automation.
Result Improved turnaround time and reduced manual reconciliation effort.
Experience
Roles, scope, impact, and AI application across products and platforms.
- 2025.09 ~ Present · Present
Queen's Smile
Full-stack Developer- Delivered feature development and operational improvements across kiosk, mobile, web, and admin products
- Built a content operations platform covering festival data intake, AI cardnews generation, Canva handoff, and scheduled Instagram publishing
- Implemented a Firebase-based commerce operations system spanning orders, payment webhooks, reconciliation, and SMS job queues
- Developed an integrated workforce management dashboard with event-level staffing visibility, role-based evaluations, and admin editing flows
- Designed and implemented a real-time waiting system covering registration, calling, entry handling, notifications, and operational metrics
- Developed and deployed an internal settlement statement site with AI support
- 2025.07 ~ 2025.07 · 1 weeks
Queen's Smile
Contract Developer- Delivered QR and barcode scanner integration
- Handled RS232 serial communication via SerialPort and event-based ingestion
- Implemented prefix-based parsing for variable-length payloads
- Applied regex validation and data sanitization for scans
- Synchronized scanner input with React kiosk UI asynchronously
- Transmitted scan data via HTTP and reflected responses in UI state
- Implemented fallback alerts and error handling for device disconnects
- 2025.06 ~ 2025.06 · 2 weeks
Queen's Smile
Contractor- Delivered kiosk payment integration and production setup
- Built a C#/.NET HTTP plugin for tPayDaemon
- Optimized HttpClient configuration with SSL and JSON bindings
- Stabilized payment requests on /Auth and /Cancel endpoints
- Embedded Chromium (CefSharp.WinForms) and implemented JS↔C# bindings
- Configured JavascriptObjectRepository and Chrome API communication
- Integrated EMV card terminals via serial port with ACK handling
- Implemented POS autofill, debugging logs, and fallback handling
- 2022.04 ~ 2025.05 · 3 years 2 months
Inno3D
Platform Team Senior Researcher- Designed and delivered real-time ordering, 3D file viewing (three.js), login persistence, and partner network features
- Deployed high-availability services on AWS EC2, RDS, and load balancers
- Implemented JWT authentication with OTP and Nest.js Guards for data protection
- Shared sessions with Redis and scaled with RDS replication
- Built 1:N real-time group chat using WebSocket and Bull Queue for high traffic
- Designed and implemented a queueing system for reliable task processing
- Automated AWS IAM and Git environment setup
- Improved defect resolution efficiency by 40% using Jest-based tests
- 2021.08 ~ 2022.01 · 6 months
HappyMade
Dev Team Lead- Delivered admin and user portals for an internal exchange service in PHP
- Integrated MySQL data and resolved production defects
- 2021.05 ~ 2021.08 · 4 months
Han Communication
Developer- Maintained client websites and authored storyboards
- Delivered full-stack client sites on Cafe24
- https://hanleeon02.cafe24.com/main/
- 2020.09 ~ 2020.11 · 3 months
BeFle (BusinessPlus)
Corporate Researcher- Redeveloped the company website and delivered an admin panel
- Implemented PHP/MariaDB backend and JS/HTML/CSS3 frontend
- Built notice, gallery, and video modules
- Delivered end-to-end web publishing
- http://www.businessplus.co.kr/
- 2017.01 ~ 2018.07 · 1 year 7 months
Hanil Networks
Business Support Staff- Managed departmental costs, budgets, marketing, and planning
- Supported general affairs, accounting, document management, procurement, and ERP operations
Skill Radar
Balanced strengths across product engineering, systems design, delivery, and AI integration.
Front-end
88%
Next.js, React, UI systems
Back-end
84%
Nest.js, APIs, data modeling
Cloud
78%
AWS, CI/CD, observability
Systems
72%
Kiosk and device integration
Collaboration
86%
Cross-team execution with security focus
A clear working process for short and mid-sized projects
The goal is to reduce ambiguity early, move quickly during implementation, and finish with a handoff the client can actually use.
01
Scope and priorities
Clarify business goals, must-have pages or features, timeline, and what success should look like after launch.
02
Build and review
Design the structure, implement front-end and back-end work, and review milestones before the full release.
03
Launch and polish
Finalize QA, deploy, connect analytics and forms, and tighten performance and UX details that affect trust.
04
Handoff and support
Provide documentation, cleanup notes, and a practical transition path for the next internal or external maintainer.
Typical deliverables
- Responsive pages optimized for desktop and mobile
- Admin or API wiring where the project requires it
- Deployment, analytics, and operational basics
- Follow-up fixes after launch if included in scope
Project shapes that work well
- Corporate site renewals with stronger positioning
- Marketing pages that need inquiry conversion
- Internal dashboards and workflow tools
- Selective AI-enabled features with clear ROI
Hiring Snapshot
A concise, decision-ready profile.
- Full-stack delivery across web, mobile, kiosk, and admin products.
- Proven experience in platform design, real-time systems, and integrations.
- Emphasis on reliable delivery, UX quality, and maintainable code.
- Actively leverage AI to improve efficiency and quality.
Contact
Please reach out by email, or review my work on LinkedIn and GitHub.
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