Jeong Woo Chang

Jeong Woo Chang

I build things for the web.

Software Engineer with 12 years of experience specializing in client-side engineering at Meta, Microsoft, and high-growth startups. Currently building high-performance UI foundations as a Founding Engineer at Lightfield.

Experience

2025 —
Lightfield logo

Lightfield (Pivoted from Tome) · Founding Engineer

Architected core CRM views (Table, Kanban, List) and design system using virtualization to handle 1M+ records at 60fps. Optimized Interaction to Next Paint (INP) using the Scheduler API, and migrated build tooling to Biome to boost local dev speed by 10x and cut CI build times by 75%.

2022 — 25
Tome logo

Tome · Senior Software Engineer

Designed and implemented Y.js (CRDT) collaborative document editor with real-time UI synchronization. Reduced client-side bundle size by 50% and optimized GraphQL response times by 90%, resulting in a 15% increase in user retention.

2021 — 22
Meta logo

Meta · Senior Software Engineer

Architected Instagram's first native checkout bridge, establishing standard cross-app commerce UI integration patterns for Facebook, Messenger, and WhatsApp. Prototyped next-gen React Native rendering systems (ReMSYS).

2020 — 21
DocuSign logo

DocuSign · Software Engineer

Co-led company-wide accessible React UI component library adoption across 6 product teams. Designed and built 'Signing Insights' document telemetry dashboard using React, TypeScript, and D3.js.

2016 — 20
Microsoft logo

Microsoft · Software Engineer

Designed 20+ accessible (a11y) UI components for the Azure Portal Design System, utilized by thousands of portal extensions. Engineered the Portal SDK, custom hosting layers, and streaming response architectures.

2011 — 13
ZooQoos logo

ZooQoos · CTO & Co-founder

Architected a real-time SPA utilizing Node.js, Socket.io, and Redis. Engineered zero-downtime automated deployment systems on AWS to support early customer scale.

B.S. Computer Science — University of Illinois at Urbana-Champaign

What I Do

UI Architecture & Design Systems

Extensible component libraries, SDKs, strict accessibility (a11y) compliance, and robust API boundaries for multi-team monorepos.

Web Performance & Platform

Tuning Core Web Vitals (LCP, INP), viewport virtualization, Scheduler API task chunking, build pipeline optimization (Biome), and Node.js V8 heap profiling.

Real-time & Collaborative UI

State-machine client synchronization, conflict-free replicated data types (Y.js/CRDT), WebSockets, and optimistic UI updates for near-instant rendering.

AI-Native User Interfaces

Streaming agentic chats, concurrency-safe UI state machines, AI model integrations, and highly productive workflows leveraging AI development tools.

Technologies

React · Next.js · TypeScript · Node.js · GraphQL · Y.js (CRDT) · D3.js · WebSockets · CSS/Tailwind · V8 Engine · Vercel · Biome · CI/CD · PostgreSQL · AWS

Get in Touch

Always happy to connect and talk about interesting problems.