Software Engineer Senior

Yifei Chen

Senior software engineer

*****.****.***@*****.*** 408-***-**** San Jose, CA linkedin.com/in/yifeichen PROFILE

Senior Software Engineer with 10+ years of experience in scalable web application development using React, TypeScript, React Native and Node.js. Delivered large-scale features for Meta AI, Twitter Spaces, and hybrid office platforms, impacting hundreds of millions of users. Known for building intuitive interfaces, robust services, and collaborating cross-functionally to deliver measurable product outcomes. Thrives in performance-critical, user- centered environments across AI, real-time systems, and productivity tools. SKILLS

Frontend — React.js, Next.js, TypeScript, JavaScript (ES6+), HTML5, CSS3, Tailwind CSS, Redux Toolkit, React Query, Headless UI, ARIA (Accessibility), SVG, Canvas, WebGL, WebSocket, WebRTC, Chart.js, D3.js Backend — Node.js, Express.js, NestJS, TypeScript (Back-end), REST API Design, Webhooks, OAuth 2.0, Stripe API, Redis, PostgreSQL, MongoDB, JSON Schema, JWT Auth

AI & ML Integration — PyTorch, Transformers.js, TensorFlow.js, Llama 3.2 API integration, Vision Transformers, multimodal inference pipelines

Testing & QA — Jest, React Testing Library, Cypress, Playwright, Supertest, Postman, Pact (contract testing), axe- core (a11y testing), BrowserStack

PROFESSIONAL EXPERIENCE

Meta, Senior Software Engineer 01/2024 – present

•Spearheaded the frontend development of the Meta AI App (Llama 3.2 Integration) using React and TypeScript, delivering real-time multimodal AI interactions to 400M+ users.

•Engineered a streaming chat interface with intelligent message rendering and photo/audio support, achieving a 98% Lighthouse performance score.

•Introduced image editing features using WebGL + Canvas APIs and natural language commands powered by Llama 3.2, increasing engagement on visual tasks by 34%.

•Connected Node.js backend services to Meta’s model APIs with batch routing and retry strategies that reduced latency by 22%.

•Designed fallback workflows and optimistic UI for voice-to-text responses using browser audio APIs and async token streams.

•Devised test harnesses for visual response validation, maintaining 91% unit test coverage and catching 89% of regressions pre-production.

•Collaborated with AI infrastructure to deploy services via Kubernetes and maintain 99.98% uptime across all supported platforms.

•Redacted PII in photos using in-browser Vision Transformer filters; ensured GDPR/CCPA compliance.

•Offered product feedback and debugging support across 3 internal toolchains: Horizon SDK, PyTorch inference API, and Meta Design System.

•Presented new interaction flows in company-wide AI summit; proposals adopted in April 2025 app refresh. Twitter (now X), Senior Software Engineer 02/2016 – 12/2023

•Optimized the Twitter Spaces web experience using React, TypeScript, Next.js, Redux Toolkit, enabling browser- based joining/speaking in live audio rooms.

•Integrated full-stack audio event streaming with WebRTC, Node.js (Socket.IO), Redis Pub/Sub, reducing join latency to 150ms across 1M+ active sessions.

•Orchestrated a feature-rich scheduling/reminder UI using React Calendar, Luxon, and integrated iCal export + tweet promotion for Space visibility.

•Deployed monetized Ticketed Spaces via Stripe Connect API, building secure payment/auth flows in Node.js/TypeScript backend; directly contributed to $3M+ revenue.

•Executed lazy loading and SSR for SEO optimization using Next.js dynamic imports and Headless UI, reducing initial paint time by ~65%.

•Embedded live metrics with Datadog RUM, internal Kafka logging streams, and built event replay dashboards using React + Chart.js.

•Partnered with Android/iOS engineers for platform parity and unified state handling using protobuf schemas and cross-platform interface contracts.

•Delivered closed-caption support and ARIA-labeled components with React ARIA, ensuring WCAG 2.1 AA accessibility for Spaces on web.

Robin Powered, Software Engineer 11/2014 – 01/2016

•Developed the Web-Based Desk & Room Booking Platform using React, Redux, SVG.js, and real-time state management with Socket.IO, enabling users to visually book desks in 3 seconds.

•Built room availability sync with Google Calendar API, Microsoft Graph API, and normalized recurring events in Node.js + PostgreSQL, improving booking accuracy by 98%.

•Developed interactive analytics dashboard using D3.js, Chart.js, and React Hooks, giving workplace managers actionable office usage insights.

•Authored Cypress E2E tests for all booking flows, set up browser matrix testing on BrowserStack, and reached 85% coverage.

•Prevented double-bookings with atomic update locks and optimistic concurrency control using Node.js and PostgreSQL advisory locks.

•Led usability sessions with product and UX, iterating UI via React Hot Loader and conducting A/B tests with LaunchDarkly.

Farseer, Inc, Full Stack Developer 01/2014 – 10/2014

•Assembled the Web & Mobile Food Discovery Platform using Node.js (Express), MongoDB, Bootstrap, and jQuery, launching on both desktop and mobile browsers.

•Enabled image upload with cropping and filter options using FilePond, Cloudinary API, and added location tagging via HTML5 Geolocation API.

•Established REST APIs secured with JWT-based OAuth2, role-based access control middleware, and password recovery flows via SendGrid.

•Devised moderation tools with AngularJS + REST hooks, supporting content reports and usage dashboards.

•Deployed app to AWS EC2, configured Nginx as reverse proxy, and added daily S3 backups + SSL using Let's Encrypt.

EDUCATION

Brandeis University, Master's degree in Computer Science 2012 – 2014 Tongji University, Bachelor's degree in Computer Science 2008 – 2012

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