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WinToo

One-person development studio · WinToo

From idea to shipped app,
one developer accountable end to end.

Flutter apps, web frontends and backend APIs. What you say in the kickoff meeting becomes code without a game of telephone. Since 2024, WinToo has been run by developer Gihyeon Kwon, who consults, builds and deploys personally. Today Claude is part of every step of that process, and three products of our own have shipped to the App Store.

Start a projectSee services
  • iOS & Android from one Flutter codebase
  • React / Next.js web frontends
  • FastAPI · Node.js · Kotlin backends
  • Claude-native development process
Code on a laptop screen — WinToo, one-person development studio

Services

Everything a product needs,
from app to server.

A smartphone showing a mobile app screen

  • Mobile app development

    One Flutter codebase, released on iOS and Android at the same time. Store review and release handled with you.

    • Flutter · Dart cross-platform apps
    • Android native (Kotlin) integration and plugin development
    • App Store · Google Play release support
    • Push notifications, social login, payments and other core integrations

  • Web frontend

    From landing pages to admin dashboards: fast, search-friendly web products.

    • React · Next.js · TypeScript
    • Lightweight Svelte apps
    • Static sites tuned for SEO and Core Web Vitals
    • Modern hosting on Cloudflare, Vercel and similar platforms

  • Backend & API

    Apps need a server to be real. Auth, databases and realtime features designed together with the client.

    • Python (FastAPI · Django) · Node.js · Kotlin (Spring)
    • REST API design, authentication and authorization
    • Realtime features on WebRTC and WebSocket
    • Database design and deployment setup

  • Maintenance & technical advice

    Improving apps already in production, code review, performance fixes. We also take over projects started by other teams.

    • Taking over and improving existing Flutter · Android projects
    • Performance optimisation and bug fixing
    • Architecture review and technology selection
    • Ongoing maintenance after launch

Claude-native development process

A one-person team
that works with Claude

WinToo uses Anthropic's Claude (Claude Code) across the entire development process. A human sets direction and owns the outcome; Claude adds speed and breadth of review. This website was planned, implemented and reviewed the same way before deployment.

  1. 01

    Requirements

    Meeting notes become a feature list and scope document with Claude, surfacing missing scenarios and edge cases early.

  2. 02

    Design & prototype

    Screen flows and data models are drafted quickly, shown to you, and revised on the spot.

  3. 03

    Parallel implementation

    App, web and server work is split across several Claude agents and integrated by the developer. One person, the pace of a small team.

  4. 04

    Review & testing

    An independent review agent checks code, accessibility, SEO and security settings before the developer signs off.

  5. 05

    Documentation & handover

    Structure and operations are written down so another developer can take over without friction.

Final judgement and responsibility always sit with the developer. Claude is a tool, not a substitute.

Portfolio

Our own products,
live on the App Store

Products WinToo planned, designed, built and shipped end to end. Every fact below comes from the public App Store listings.

  • Woori Hanpun app icon

    Woori Hanpun (우리 한푼)

    A shared household ledger you join with one link

    An iOS app for families, couples and roommates to record income and spending together. Tap an invite link to join a group without signing up, and see each member's spending against their monthly goal on a dashboard.

    • Shared ledgers per group with member roles
    • Join by invite link, no account required
    • Dashboard of each member's spending vs. monthly goal
    • Calculator-style keypad and 20 spending categories
    • Monthly calendar of income and expenses by day
    Platform
    iOS
    Category
    Productivity
    Released
    March 2026
    Price
    Free
    View on the App Store — Woori Hanpun (우리 한푼)
    • Woori Hanpun group start screen
    • Dashboard of spending against monthly goals
    • Calendar of income and expenses by day
  • Remote Pad app icon

    Remote Pad

    Turn your iPhone into a wireless trackpad for your Mac

    Finds a Mac on the same Wi-Fi via Bonjour, connects with one tap, and turns the iPhone screen into a trackpad. Built as an iOS app plus a macOS helper app, with the realtime link between the two implemented from scratch.

    • Bonjour discovery, no IP addresses to type
    • Standard trackpad gestures: tap, drag, two-finger scroll, three-finger swipe
    • Mission Control, App Exposé and desktop switching
    • Cursor acceleration from 0.3× to 3.0× and orientation lock
    • Automatic reconnection with back-off when the network drops
    Platform
    iOS + macOS helper
    Category
    Productivity
    Released
    May 2026
    Price
    Free
    View on the App Store — Remote Pad
    • Remote Pad screen 1
    • Remote Pad screen 2
    • Remote Pad screen 3
  • Fan Chant app icon

    Fan Chant (팬찬트)

    Practise concert fan chants before the show

    An iOS app for fans nervous about chants before their first concert, groups who want to rehearse together, and anyone who wants concert energy at home. Focused on making every chant easy to follow and repeat.

    • Practise concert fan chants
    • Flows for rehearsing alone or with friends
    • A cheering mode that brings concert atmosphere home
    Platform
    iOS
    Category
    Entertainment
    Released
    June 2025
    Price
    Free
    View on the App Store — Fan Chant (팬찬트)
    • Fan Chant screen 1
    • Fan Chant screen 2
    • Fan Chant screen 3

About

Gihyeon Kwon, the developer behind WinToo.

I have built mobile apps with Flutter and Android (Kotlin), and I implement the web frontends and backends those apps need. I also run three products I planned and shipped to the App Store myself, so I have been through the whole path from idea to live service more than once.

WinToo (윈투) is the one-person development studio I started in 2024 on that experience. The goal is to be the partner that helps small teams and individuals shape an idea and takes responsibility for a working result.

권기현Gihyeon Kwon

Flutter Developer · Founder, WinToo

Source code in an editor

Timeline

From Android native to Flutter,
a steady track record

The development history leading up to WinToo. All dates match public repositories and store records.

  1. 2019

    Started Android (Kotlin) development

    Built Kotlin native apps and a realtime video chat service on WebRTC and sockets.

  2. 2021

    Moved to Flutter

    Adopted Flutter as the main stack to ship iOS and Android from one codebase.

  3. 2023.12

    Published Flutter plugin gh_asset_pre_cache

    A plugin that precaches asset images automatically to speed up first paint, published on pub.dev.

  4. 2024

    WinToo begins

    Started app, web and backend work as the one-person studio WinToo, alongside Kotlin backend and TypeScript web projects.

  5. 2024.06

    Published Flutter i18n plugin gh_i18n

    A plugin that makes localisation in Flutter apps straightforward, published on pub.dev.

  6. 2025.06

    First own product, Fan Chant, on the App Store

    An iOS app for practising concert fan chants, taken from idea to release solo.

  7. 2026.03

    Launched Woori Hanpun on the App Store

    A shared ledger app; version 1.2.0 followed in May.

  8. 2026.05

    Launched Remote Pad: iOS app plus macOS helper

    An app that turns the iPhone into a Mac trackpad, built for both platforms.

Contact

Let's talk about
your project.

Email is the fastest way to reach WinToo. A rough idea is enough to start; we aim to reply within one to two business days.

Email

dev.gihyeon@gyeony.comUse the Korean inquiry form

What to include

  • A short description of what you want to build
  • Links to any apps or services you are using as reference
  • Your target launch date
  • The current state of an existing project, if there is one