Basic Info
- Name
- Gwangsoo Choi
- Age
- Born 1988
- Location
- Shibuya, Tokyo, Japan (2018.06~)
- Languages
- Korean, Japanese, English
- Education Β· Military service
- Namseoul University β Dept. of MultimediaROK Army 2nd Infantry Division, Sergeant, Honorable Discharge
- Hobbies
- Weight training (2009.01~)CrossFit (2026.05~)
- Contact
- gwsoochoi@gmail.com
Tech Stack
2013 β 2026
'14'17'20'23'26
Industry
SI/SE8y
Japanese Language School1y
Startup4y
Freelance4y
Solo Product2y
Backend
Java Spring8y
Ruby on Rails6y
Web
HTML13y
JSP7y
JavaScript7y
React6y
TypeScript2y
Next.js1y
Mobile
Flutter1y
Swift1y
Kotlin1y
Database
Oracle7y
MySQL4y
PostgreSQL3y
PostGIS3y
Cloud
Google Cloud Platform6y
Supabase2y
Cloudflare R22y
Docker6y
Product Operations
Git6y
GitHub Actions6y
Design
Figma2y
Claude Design1y
GPT Image 21y
AI
Claude Code2y
Codex1y
noneused
Career
Solo Product
Scope: Planning β UI/UX Design β Development β Infrastructure β Store Review β Operations β Marketing (all areas)
2025.01 ~
- A location-based social app for the LGBTQ+ community β discover people nearby on the map and connect through Shouting, meetups, and 1:1 messaging
- A shared Rails 8 + PostGIS API running alongside SwiftUI on iOS, Jetpack Compose on Android, and an Admin WebApp
- 6 languages with AI auto-translation, plus a store registration β approval flow as the base for a B2B revenue model
- A 2-person team with one design/planning member β I lead product direction and all technical areas
Achievements
- Built an AI-powered workflow integrating Claude Code into requirements, code review, and TDD in a 2-person team β enabling a solo engineer to ship 2β3 features/refactors per week and reaching 1,000 users and 100 concurrent users within 6 months of launch
- Differentiated from grid-based LGBT apps by designing a Map-First home screen that displays both users' 24h auto-expiring location broadcasts (Shouting) and business listings on the map, built on a Rails API with PostGIS proximity search (originally Flutter, now migrated to native SwiftUI and Jetpack Compose). Averaging 10 new daily users since Shouting launch
- Built a GitHub Actions CI/CD + TDD automation pipeline, releasing 6 major versions over 8 months from v1.0.0 with zero store rejections, establishing a stable iteration cycle
2026.06 ~
- An iOS Β· iPadOS kids app that turns what a child says into a coloring page. Live on the App Store (v1.3.1)
- SwiftUI Β· PencilKit app on a Rails 8 API β speech recognition, safety checks, and generation are orchestrated entirely server-side; the app only captures and renders
- Built for the Kids Category: no kid logins, no ads, minimal data, with accounts, purchases, deletion, and consent behind a guardian lock
- Credit-based IAP and promo codes, GCP Cloud Run Β· Cloud Tasks, Cloudflare R2, APNs, and an Admin console
- Available in Korean, Japanese, and English
Achievements
- Shipped v1.0.0 to the App Store about a month after starting development, then released continuously through v1.3.1 over the following 6 weeks
- Put server-side moderation at every stage of the generation pipeline, failing closed on unsafe requests β passing Kids Category review with zero rejections
- Covered API, Admin, and iOS with automated tests (426 API RSpec cases / 248 iOS cases) so every release is regression-checked even as a solo developer
Startup
KabuKuStyle Inc.
Full-time β Freelance- Subscription travel platform HafH β Backend development
- Designed and implemented coin allocation and pricing migration for new user plan rollouts
- Designed and implemented promotion logic including plan-specific bonus coins, discounts, and VIP benefits
- Designed, maintained, and implemented Admin features and CS support tooling
- Connected multiple OTA (accommodation) APIs for real-time inventory and pricing sync
- Rails API server design and development, GCP infrastructure operation
- Resolved user inquiries via On-call and handled production incidents
- Involved in the full cycle from planning to deployment in a small agile team
Achievements
- During a full plan restructuring (New Standard launch, coin system migration) with active users, completed zero-downtime migration of existing user coin balances and pricing via phased rollout + batch processing
- Designed and implemented bonus coin, discount rate, VIP condition, and first-come-first-served logic for campaigns (first-month-free, Seoul flight invite, Tsumitabi discount), contributing to ~1,000 new user acquisitions per campaign
- Built user lookup, coin adjustment, and booking status features in Admin that CS previously had to request from engineers β significantly reducing CS-to-engineer request volume and dev overhead
PPB International
Freelance- Minerva Investment Info Platform development
- Led as PL in a 3-person team β designed and built the full backend, DB, and REST API
- Executed data integration and migration from external platforms
Achievements
- Led as PL in a 3-person team to complete full backend design and development of the Minerva platform
- Successfully completed data integration and migration from external platforms
SI/SE
LibGate Inc. (Tokyo)
Freelance- Participated in SMBC Furusato Tax Site renewal development
- Participated in backend development for user registration, login, and profile management
Achievements
- Completed backend development for user registration, login, and profile management
Axrossroad Inc. (Tokyo)
Full-time- Participated in government operations backend development under NTT DATA
Achievements
- Completed backend development contribution for large-scale government operations system under NTT DATA
Gyrosoft Inc. (Seoul)
Full-time- A company developing floor-plan design and space management solutions. Migrating an existing Windows package solution to a web service, while delivering SI-based web applications to enterprises needing the solution
- Worked in 3β4 person teams, closely collaborating across planning, design, and development throughout each project
Key Projects
Woori WON Banking
- Participated in developing internal community boards and business management content/admin for bank employees
POSTECH Space Management
- Participated in developing a system to manage booking, approval, and usage of shared campus facilities (classrooms, labs, meeting rooms)
RightBrain Inc. (Seoul)
Full-time- An SI company specializing in CRM web application development β joined major enterprise client projects
- Primary workflow: developing based on system specification documents, collaborating with PMs and designers when design adjustments were needed
Key Projects
AMORE MALL
- Developed CRM features including signup, profile management, and My Page for the all-brand integrated commerce app
Happy Point
- Developed CRM features including signup, profile management, and My Page for the 6,000+ store membership app
A Few Words
After SI/SE work, startups, and freelancing, I now run everything from planning through development and operations as a solo full-stack developer. My focus is building mobile apps that earn: I hand implementation to AI agents and own the overall system design and review myself. I also cover marketing and UI/UX design.
I care about shipping new ideas fast and reliably so the value actually reaches users, and about responding quickly to whatever friction they hit after a release. Fast delivery looping back through user feedback is what makes a product strong.
Reaching the goals of my own products comes first, so I'm not looking for full-time roles β only freelance contracts of 20β30 hours a week. If you'd like to build something fun together, get in touch.