Portfolio
Selected work
Crypto, consumer apps, and the products I build and run myself.
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Real-time Pricing & Live Charts
Owned the real-time pricing engine in the shared SDK behind the mobile and desktop apps: a new live-price endpoint with ETag caching and a 25-second price pipeline next to the 1-minute market-data one, with fallback between them. Ported the Liveline chart engine to React Native Skia and replaced every legacy chart with it, and built the rolling-number animation for balances.
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Transaction Security
Simulated WalletConnect requests with Blockaid on EVM and Solana before users sign, and turned on WalletConnect’s Verify API in Exodus’s fork of the SDK so scam dapps are flagged. Built the new transaction and signature approval screens with unsafe-transaction warnings, and EIP-7702 delegation scam flows on mobile and desktop.
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Native Reliability & Recovery
Built a crash-proof Recovery Mode that lets users get their secret phrase back even when the main app crashes, launched from an iOS Settings toggle or an Android launcher shortcut. Added screen-recording detection and screenshot blocking in Objective-C, a cancel API for Android BiometricPrompt in Java, and fixed wallet-unlock race conditions and an Android SIGSEGV.
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Video Pipeline & Stories
Built the client-side ffmpeg video compression pipeline with HDR detection, size fallback and rotation fixes, and extended the story editor with drag-and-drop media reordering and styled captions. Cut overdraw and re-renders in live-event rendering on Android, and built the pinch-to-zoom component later open-sourced on npm.
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Feed, Auth & Subscriptions
Built the new feed with a preview-and-portal reaction bar that follows each profile during swipes without Android keyboard jitter, and shipped direct messages. Introduced RTK Query alongside Redux Saga with a token-refresh middleware that dedupes concurrent refreshes, and integrated Superwall paywalls with RevenueCat.
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Saju Alley
Korean fortune readings, written to be read late, in the quiet. Designed, built and run end to end: streaming AI readings on the Claude API, Supabase auth and Postgres, Stripe and Kakao Pay payments, and web push.
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Inbound
Messages from the people you miss, arriving on your lock screen when you least expect them. An on-device scheduler at random times, iOS Communication Notifications in Swift so they arrive like real messages, and an Android boot receiver in Kotlin that re-arms them.
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Outbound
Write to someone who isn't there. Nothing leaves the device: a crash-safe local store with atomic writes, a biometric lock, and native home-screen widgets on iOS and Android.
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Luko Insurance App
Owned insurance-contract flows (update, cancel, manage) for 60–80k monthly users. Moved legacy code into shared modules, raised unit and e2e coverage, and gave internal talks on native development.
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DANO Android App
Fitness app with workout plans, video playback and analytics.
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Linkey Android Apps
Built the first seller and customer apps from scratch, including Kakao and Naver login.
About me
Get to know me
I'm a senior React Native engineer with 8+ years in mobile. I started on native Android in Kotlin, moved to React Native in 2018, and have shipped apps in crypto, dating, insurance, fitness and commerce.
I'm most useful where the JavaScript layer meets native code: real-time data, animation and rendering performance, and the security details that decide whether people trust an app with their money.
Outside client work I run Grida, a small studio where I design, build and ship my own products end to end.
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01
React Native & Performance
UI-thread animation and canvas rendering that stay smooth under live data.
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02
Native iOS & Android
Native code on both platforms: screen-recording protection, biometric prompts, crash recovery and home-screen widgets.
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03
Crypto Wallets & Security
Self-custody wallets, transaction simulation, dapp verification, and scam warnings before users sign.
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04
Architecture & Quality
Shared SDKs across mobile and desktop, data layers, and tests that keep releases calm.