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I'm a Senior Full Stack Engineer with 12+ years of experience designing, developing, and maintaining scalable web applications across SaaS, healthcare platforms, and enterprise systems. I take pride in turning complex product requirements into maintainable systems and guiding engineers through code reviews, testing habits, and design discussions. I continually cultivate a collaborative, positive, and humble work style that helps teams communicate clearly and deliver steady results. I enjoy mentoring others and finding elegant, practical solutions to hard problems.…I'm a Senior Full Stack Engineer with 12+ years of experience designing, developing, and maintaining scalable web applications across SaaS, healthcare platforms, and enterprise systems. I take pride in turning complex product requirements into maintainable systems and guiding engineers through code reviews, testing habits, and design discussions. I continually cultivate a collaborative, positive, and humble work style that helps teams communicate clearly and deliver steady results. I enjoy mentoring others and finding elegant, practical solutions to hard problems.

Thomas Zhang

Full Stack Developer, Back-End Developer, Front-End Developer, +2

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I'm a Senior Full Stack Engineer with 12+ years of experience designing, developing, and maintaining scalable web applications across SaaS, healthcare platforms, and enterprise systems. I take pride in turning complex product requirements into maintainable systems and guiding engineers through code reviews, testing habits, and design discussions. I continually cultivate a collaborative, positive, and humble work style that helps teams communicate clearly and deliver steady results. I enjoy mentoring others and finding elegant, practical solutions to hard problems.…I'm a Senior Full Stack Engineer with 12+ years of experience designing, developing, and maintaining scalable web applications across SaaS, healthcare platforms, and enterprise systems. I take pride in turning complex product requirements into maintainable systems and guiding engineers through code reviews, testing habits, and design discussions. I continually cultivate a collaborative, positive, and humble work style that helps teams communicate clearly and deliver steady results. I enjoy mentoring others and finding elegant, practical solutions to hard problems.

Available to hire

I’m a Senior Full Stack Engineer with 12+ years of experience designing, developing, and maintaining scalable web applications across SaaS, healthcare platforms, and enterprise systems. I take pride in turning complex product requirements into maintainable systems and guiding engineers through code reviews, testing habits, and design discussions.

I continually cultivate a collaborative, positive, and humble work style that helps teams communicate clearly and deliver steady results. I enjoy mentoring others and finding elegant, practical solutions to hard problems.

Skills

Experience Level

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

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Expert

Language

English

Fluent

Work Experience

Senior Full Stack Engineer at Thoughtworks

November 2, 2023 - March 2, 2026

Developed scalable React, Node.js, and NestJS modules for cloud-based SaaS transformation projects, converting complex product workflows into reusable services and improving feature delivery consistency across distributed engineering teams. Designed backend RESTful APIs with TypeScript, Python services, PostgreSQL, and Redis for high-volume client platforms, reducing processing latency by 30% while keeping business rules testable and easier to extend. Implemented secure authentication and authorization flows using AWS Cognito, JWT, role-based access controls, and API Gateway, strengthening account protection while simplifying login, session handling, and permission checks across frontend and backend systems. Optimized application performance by profiling React rendering paths, database queries, and Node.js service bottlenecks, improving system throughput by 23% and reducing avoidable API retries during peak SaaS usage windows. Integrated AI-assisted search and workflow recommendations

Senior Software Engineer at UnitedHealth Group

November 2, 2018 - September 2, 2023

Developed large-scale health care web applications with React, JavaScript, Node.js, and Python to support UnitedHealth care and Optum service workflows used by millions of members, providers, and business customers. Implemented backend RESTful APIs, SQL data models, and secure service integrations for eligibility, claims, and care management workflows, reducing error rates by 37% through stronger validation and consistent API contracts. Enhanced authentication and data access controls using OAuth patterns, service-level permissions, and audit-friendly logging, helping protect sensitive health care information while supporting reliable access for internal operations teams. Optimized database queries, caching behavior, and a synchronous processing path for high-volume health care service requests, improving response reliability and supporting large business workflows without adding unnecessary operational complexity. Completed CI/CD, Docker, Jest, Postman, and monitoring improvements tha

Junior Software Engineer at McDonald's

February 2, 2014 - July 2, 2018

Built backend services with Node.js, Express.js, JavaScript, and MySQL for restaurant operations and delivery expansion systems, supporting order routing, menu updates, and store-level workflow automation. Created responsive web interfaces using HTML5, CSS, JavaScript, and early React patterns for operational dashboards, giving restaurant managers clear visibility into delivery activity, service timing, and daily issue tracking. Improved API reliability by debugging integration failures between ordering, payment, and fulfillment systems, reducing support escalations by 25%. Assisted senior engineers with SQL reporting, REST endpoint testing, Agile planning, and production fixes, building strong fundamentals in full-stack development while contributing features for global restaurant operations.