Jay Heo

Building Ecco's cross-platform streaming app — web, mobile, and an airline in-flight entertainment build.

• Rebuilt the app's auth model around a guest state so browsing, search, and playback work without an account — removing the signup wall raised Day-1 retention from 25% to 75%.
• Ported the web app to airline in-flight entertainment hardware (a legacy Qt browser with minimal CPU and memory) and built an MQTT-based remote control to drive it from a separate device. Demoed at the Aircraft Interiors Expo in Germany, leading to follow-up meetings with 18 airlines including Lufthansa, Etihad, and Saudia.
• Led the React Native upgrade from 0.76 to 0.84 alongside React 19 and Expo 55, driven by Android 16 KB page-size requirements and a New-Architecture-only dependency stack — using ~490 existing tests to catch regressions across iOS and Android.
• Rebuilt voice search around a proper speech-recognition state machine — stable vs. interim transcripts, intentional stops vs. dropped connections, rate-limited auto-restart — driving a 30% increase in searches after launch.
• Built the Go backend and Redis-based session logic for the analytics event pipeline, and shipped the app's first monetization path: a subscription paywall with full Stripe integration for checkout, subscription status, and webhook-driven entitlements.

• Migrated the backend from REST to GraphQL/Apollo so the frontend fetches exactly what each resume section needs instead of over-fetching across multiple endpoints.
• Built the AI resume generation flow — calculating available line space before generation, with keyword tracking so bullets don't repeat across a resume.
• Moved resume file storage off the database and onto S3 with pre-signed URLs for previews and downloads.

• Built the real-time mock interview flow — Next.js dynamic routes talking to the AI backend over WebSockets.
• Cut AI response latency from 5–10 seconds to near real-time by streaming audio over WebSockets in chunks and streaming AI responses back token by token.
• Advanced to the final round of Y Combinator's S2024 selection process out of thousands of applicants, and coordinated sprints to ship a polished app ahead of the application deadline.

• Built a portfolio view pulling a user's on-chain holdings and calculating average cost basis, current value, and unrealized gains/losses against live prices — caching CoinGecko responses to work around a low API rate limit.
• Added QR-code-based actions tied to the user's wallet address, surfacing different options depending on what the scanned code represents.