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Software engineer with 8+ years of experience building scalable, high-performance web applications across SaaS, e-commerce, observability, virtual assistant, and enterprise platforms. Deep expertise in React, TypeScript, JavaScript, and modern frontend architecture with strong API integration and performance optimization. Hands-on experience accelerating delivery and improving code quality using AI-powered development tools (Claude Code, Cursor, Codex, GitHub Copilot). Experienced defining frontend best practices, building reusable component-based systems, mentoring engineers, and partnering closely with product, design, backend, SRE, and platform teams to deliver user-centered experiences at scale.…Software engineer with 8+ years of experience building scalable, high-performance web applications across SaaS, e-commerce, observability, virtual assistant, and enterprise platforms. Deep expertise in React, TypeScript, JavaScript, and modern frontend architecture with strong API integration and performance optimization. Hands-on experience accelerating delivery and improving code quality using AI-powered development tools (Claude Code, Cursor, Codex, GitHub Copilot). Experienced defining frontend best practices, building reusable component-based systems, mentoring engineers, and partnering closely with product, design, backend, SRE, and platform teams to deliver user-centered experiences at scale.

Jianfeng Sun

Front-End Developer, Software Engineer, Web Developer, +2

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Software engineer with 8+ years of experience building scalable, high-performance web applications across SaaS, e-commerce, observability, virtual assistant, and enterprise platforms. Deep expertise in React, TypeScript, JavaScript, and modern frontend architecture with strong API integration and performance optimization. Hands-on experience accelerating delivery and improving code quality using AI-powered development tools (Claude Code, Cursor, Codex, GitHub Copilot). Experienced defining frontend best practices, building reusable component-based systems, mentoring engineers, and partnering closely with product, design, backend, SRE, and platform teams to deliver user-centered experiences at scale.…Software engineer with 8+ years of experience building scalable, high-performance web applications across SaaS, e-commerce, observability, virtual assistant, and enterprise platforms. Deep expertise in React, TypeScript, JavaScript, and modern frontend architecture with strong API integration and performance optimization. Hands-on experience accelerating delivery and improving code quality using AI-powered development tools (Claude Code, Cursor, Codex, GitHub Copilot). Experienced defining frontend best practices, building reusable component-based systems, mentoring engineers, and partnering closely with product, design, backend, SRE, and platform teams to deliver user-centered experiences at scale.

Available to hire

Software engineer with 8+ years of experience building scalable, high-performance web applications across SaaS, e-commerce, observability, virtual assistant, and enterprise platforms. Deep expertise in React, TypeScript, JavaScript, and modern frontend architecture with strong API integration and performance optimization.

Hands-on experience accelerating delivery and improving code quality using AI-powered development tools (Claude Code, Cursor, Codex, GitHub Copilot). Experienced defining frontend best practices, building reusable component-based systems, mentoring engineers, and partnering closely with product, design, backend, SRE, and platform teams to deliver user-centered experiences at scale.

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Work Experience

Software Engineer, Frontend Focused at Stealth Startup

November 1, 2025 - Present

Built and evolved production frontend features using React, TypeScript, Tanstack, Redux, HTML, and CSS, focusing on responsive interactions, predictable state management, cache consistency, and smooth user experiences. Used Claude Code and Codex to decompose ambiguous requirements, scaffold frontend components, generate implementation plans, refactor code, and accelerate delivery. Built reusable AI-assisted development workflows (prompt patterns, project rules, agents, skills, and review practices) to apply frontend best practices consistently. Reviewed AI-generated and human-written code for accessibility, security, performance, maintainability, production readiness, and test coverage. Translated complex workflow requirements into UI specifications for multi-step screens, aligning component behavior, API contracts, validation rules, state transitions, and user-facing copy. Partnered with product, design, and backend stakeholders to deliver vertical product capabilities across UI, serv

Software Development Engineer, Frontend Focus (consulting) at Uber

September 1, 2024 - September 1, 2025

Developed and maintained core frontend features for U-Monitor UI, Uber’s internal observability platform used by thousands of engineers to monitor systems, troubleshoot issues, and respond to incidents. Built high-performance, component-based frontend interfaces using TypeScript, Fusion.js, Tanstack React Query, Zustand, JavaScript, HTML, and CSS. Integrated frontend applications with backend services and designed gRPC APIs in Go to support alerting workflows and cross-system communication. Debugged and resolved complex frontend and cross-stack issues across UI behavior, data fetching, API contracts, state consistency, and web performance. Collaborated with SRE, backend, and platform teams to define alerting UX, service contracts, API standards, and developer-facing workflows. Participated in code reviews and architectural discussions focused on reliability, usability, scalability, and maintainability.

Frontend Engineer II Lead at Expedia

May 1, 2021 - May 1, 2024

Led the design and rollout of a virtual assistant platform, setting new benchmarks in user experience and ensuring peak performance and seamless user interactions. Developed responsive frontend features using React (v16+), TypeScript, JavaScript, HTML, CSS, and ES6+ for modern web applications. Implemented RESTful API endpoints in Node.js to support business workflows and maintainable service communication. Maintained and enhanced GraphQL service layers for retrieving and updating user data from MySQL. Integrated frontend with REST APIs, GraphQL services, Node.js backend services, and relational data workflows. Built, tested, and documented scalable web components using Storybook, improving reusability and consistency. Collaborated with engineer managers and UX designers to translate product specs into engineering design docs and implementation plans. Debugged compatibility, rendering, data integration, and performance issues. Mentored 2 junior engineers through implementation planning

Software Engineer (Amazon Retail) at Amazon

November 1, 2019 - April 1, 2021

Spearheaded migration of a content management tool and resolved critical pipeline bottlenecks. Built and optimized frontend modules for large-scale content management platforms using React, TypeScript, HTML, CSS, and ES6+. Refactored legacy React/TypeScript modules by consolidating state management and data-fetching logic, reducing technical debt and improving page performance and responsiveness. Developed reusable UI micro-components and contributed to component-based frontend architecture. Debugged frontend issues, pipeline bottlenecks, operational defects, and platform gaps to improve reliability. Assessed impact of software changes on workflows, dependencies, and migration milestones during platform modernization, using dashboard metrics to identify performance opportunities and recommend improvements. Participated in design discussions, UAT support, architecture conversations, and code-quality improvements. Completed two key migration milestones ahead of projected timelines.

Frontend Engineer (Consulting) at Apple

June 1, 2019 - November 1, 2019

Developed dynamic and adaptable dashboard functionality in React, optimizing performance and scalability for a mission-critical enterprise application. Collaborated across onsite and offshore development teams to deliver complex projects. Built dashboard features using React and Redux to improve usability, scalability, and maintainability. Developed user-centered interfaces for data-heavy workflows with clarity and responsiveness. Ensured frontend quality by maintaining consistent implementation patterns and reliable UI behavior across enterprise workflows.

Software Automation Engineer at Leica Geosystems

October 1, 2016 - January 1, 2019

Designed and implemented scalable JavaScript test suites, increasing automation coverage by automating 90% of manual processes. Led the creation of Python-based internal tools, boosting engineering team productivity by 100%. Generated automation scripts that reduced manual workload by 90% and improved daily efficiency. Elevated test coverage and regression quality by architecting reliable and reusable automated tests.

System Engineer at Blackfire LLC

September 1, 2015 - October 1, 2016

Analyzed system weaknesses and constraints to identify improvement opportunities. Wrote automation scripts that increased daily productivity. Created Python-based internal tools to improve efficiency and reduce engineering workload. Utilized UNIX commands and shell scripting for simplified testing and logging processes. Conducted network assessments in complex conditions (including low signal strength) to ensure network reliability.