Full-stack developer based in Lake Forest, California. I build mobile apps,
web platforms, and desktop tools — with a QA background that means I ship things
that actually work. Currently building in React Native, Next.js, TypeScript, and Python.
A mix of mobile apps, web platforms, desktop tools, and APIs — built with real users in mind.
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Full-StackPrivate
Private Streaming Platform
Built a Netflix-style streaming platform with PIN-protected profiles, hero carousel, section-based content library, and last-watched tracking. Includes a complete media pipeline — ffmpeg for codec conversion (HEVC → H.264, multi-channel audio downmix), boto3 multipart for large file uploads to Cloudflare R2, and yt-dlp for content sourcing. Deployed across two isolated Cloudflare accounts. Ran a full security audit identifying and fixing 10 issues before launch.
React Native companion to the private streaming platform. PIN-protected profile switching, R2 direct video playback, YouTube embed, bookmark management, full-text search, and an in-app admin panel — all built with Expo SDK 56 and TanStack Query.
Desktop app translating text into 5 languages with phonetic guides, ambiguity detection, tone/domain selectors, and SQLite-persisted history. Two-pass AI translation for natural output.
Social media dashboard with Google OAuth, Shopify Admin API integration, and Meta/Instagram OAuth. Pulls shop snapshots and live follower counts in a unified view.
TypeScript REST API that calculates exact silence buffer needed to keep multilingual video overlays in sync (±80ms). Handles Korean, Spanish, and Hindi character timing via ElevenLabs.
Encrypted wellness app with a private journal, guided breathing, stretch routines, and a Feelings Journal — 48-emotion wheel, tappable prompts, biometric lock, and AES-256-GCM encryption. Android APK built and deployed.
Python Flask web app with city search, current conditions, and 5-day forecast. Includes response caching to minimize API calls and a responsive mobile-friendly UI.
Installable PWA course app teaching practical AI tool usage — ChatGPT, Claude, Gemini, Perplexity. Has quizzes, progress tracking via localStorage, and works fully offline.
I'm Kwang Yoon, a full-stack developer based in Lake Forest, California.
My background in QA testing gave me something most developers don't have from the start —
a deeply ingrained habit of thinking about what breaks, not just what works.
I've built mobile apps deployed to production, full-stack web platforms with third-party OAuth,
a cross-platform desktop app in Tauri/Rust, Python backends, and TypeScript APIs.
I build across the whole stack because I care about how the pieces fit together.
Outside of code, I run a multilingual wellness YouTube channel and speak four languages —
which is why a lot of my projects have internationalization built in from day one.