← David S Choi

Resume

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I build consumer and B2B web products and stay in the code: tech plan, system design, and ownership through to production monitoring. Accessibility by default, AI-assisted throughout.

Experience

Sep 2025presentRemote

Wander

Staff Product Engineer
  • Led the full redesign of the consumer marketplace — home, search, property pages, mobile checkout — on a new design system; drove an 8% lift in property-to-checkout conversion, roughly $2.3M/year in incremental GBV.
  • Own Discounts end to end: Prisma schema, Fastify APIs, operator dashboard, and guest checkout across a Next.js site and a multi-tenant Astro platform, including per-line-item allocation for stacked coupons.
  • Built the host Listings editor (backend APIs plus React dashboard) enabling self-serve property edits, and launched a direct-booking channel generating ~$100K/month by bypassing Airbnb and Vrbo commissions.
  • Rolled out property-specific cancellation policies and house rules across web, mobile, and partner sites.
  • Contributed reusable booking-flow primitives to the shared design system, and a CI pipeline that surfaces bundle-size and Lighthouse deltas on every PR.
Jul 2024Aug 2025Remote

Nextdoor

Senior Software Engineer · Ad Formats & Foundations
  • Migrated all US ad formats off Google Ad Manager onto Nextdoor's own platform, retaining $2M/year in ad revenue and removing a deprecated dependency.
  • Refactored the highest-traffic ad slot rendering pipeline: ~30% faster time-to-render and better above-the-fold viewability, projected at $200K+/year incremental revenue.
  • Designed a unified ad formats architecture, consolidating every format into a shared library adopted across the monolith and Ad Manager.
  • Integrated an LLM to pre-fill ad descriptions and image metadata, cutting manual entry time ~40%; built a Cloudinary-AI smart-cropping tool that won the peer-voted company hackathon.
  • Shipped the Carousel format, multiple-choice lead-gen fields, and multi-aspect-ratio support; owned Cypress E2E and Storybook visual regression for every web ad format.
May 2023Jun 2024Remote

Yahoo

Senior Software Engineer · Fantasy Sports
  • Led the React Player Card initiative on a high-traffic fantasy surface, integrating the Sports Design System with internal player-stats APIs.
  • Modernized Fantasy Football Draft and Matchup Recap, embedding LLM-generated content and migrating the UI from a PHP monolith to React.
  • Designed an internal moderation framework to validate LLM output for quality and compliance, enabling safe AI rollout at scale.
  • Architected Google Ad Manager integration across PHP and React repos, lifting ad viewability 12% across tens of millions of monthly pageviews.
Oct 2021Apr 2023Remote

Lyft

Senior Software Engineer · Memberships
  • Tech lead for Lyft Pink: owned the consumer web sales flow, checkout, and internal tooling end to end, including mobile webviews embedded in the native iOS and Android apps for millions of riders.
  • Rebuilt the membership flow into a reusable subscription platform powering internal teams (Transit, Bikes & Scooters) and partners including Chase, CitiBike, GrubHub, Delta, and Amazon.
  • Migrated the CX & Trust tool to current infrastructure and consolidated membership data, cutting support handling time 40% and cancellations 15%.
  • Moved web services to Lyft's in-house Node architecture, lifting SEO, performance, and a11y Lighthouse scores from ~60 to 95+.
  • Conducted 100+ technical interviews and led interview improvement groups on accessible interviewing and grading criteria.
Mar 2018Sep 2021Irvine, CA

Twitch

Front End Engineer II (L5) · Creator
  • Led the architecture migration of the Creator Experience platform from .NET/jQuery to Go/React, with a full redesign aligned to the internal design system.
  • Led the Creator Dashboard analytics suite — Stream Summary, Achievements, Discovery, Engagement, Earnings — and abstracted a reusable graphing component adopted across applications.
  • Sole frontend engineer across five applications, four of them built from zero to production.
  • Introduced TypeScript and Jest/Enzyme, enabling CI with 99.9% uptime; implemented an Apollo Client wrapper for state, queries, and JWT auth.
Sep 2016Feb 2018Los Angeles

Solver

Developer
  • Led a page-by-page migration from AngularJS to Angular 5 with a zero-downtime deprecation strategy.
  • Cut initial bundle size from 20MB to 2.5MB and time-to-interactive from 17s to 5s via lazy loading, AoT compilation, and tree shaking.
Sep 2012Aug 2016San Francisco

Switchfly

Web Developer
  • Built a reusable component architecture that reduced client branding from 80 hours to 2, enabling rapid sales demos for JetBlue, Southwest, United, American Express, and Mastercard.
  • Automated 200+ test cases via a Fluent interface on Selenium/Jenkins, cutting QA regression time from 60+ hours to ~30 minutes.

Skills

Languages & frameworks

TypeScript, JavaScript, React, React Native, Next.js, Astro, Vite, Tailwind, Vanilla Extract, Storybook, design systems, accessibility, Node.js, Fastify, GraphQL, Prisma, PostgreSQL

Infrastructure & tooling

Vercel, Cloudflare Workers, AWS, CI/CD, Vitest, Jest, Cypress, Claude Code, Cursor, MCP

Education

University of California, Berkeley
B.A. Sociology · 2011

Interests

Basketball, puzzles, nature, the Los Angeles Lakers, and the Señor Sisig California spicy pork burrito with egg.