Yuan Chen
San Jose,CA
Summary
7 years of experience in the IT industry as a Full stack developer with web-based applications included E-Commerce and Retail web platforms projects.
- Strong experience designing and building scalable backend systems using Node.js, Express.js, REST APIs, and GraphQL (Apollo Server) in production environments.
- Proficient in developing RESTful services and GraphQL APIs, including schema design, resolvers, queries, and mutations.
- Hands-on experience optimizing API performance using caching, batching (DataLoader), and query optimization techniques.
- Experienced in integrating backend services with MongoDB (NoSQL) and SQL databases, including data modeling and schema design.
- Built end-to-end data pipelines from API layer to database, ensuring efficient data flow and consistency across services.
- Developed and maintained backend logic for data processing, validation, and asynchronous operations using JavaScript (Node.js).
- Experience consuming and integrating third-party APIs and web services (REST/JSON) within backend systems.
- Proficient in building and integrating full-stack applications using React, Next.js, and Node.js, ensuring seamless frontend-backend communication.
- Strong understanding of JavaScript fundamentals and asynchronous programming, enabling efficient and scalable application development.
- Experience working in Agile Scrum environments, using tools like Jira to manage tasks and deliver high-quality software collaboratively.
- Familiar with data analysis and modeling using Python and SQL, supporting backend data-driven features.
- Hands-on experience with Apollo GraphQL client and server, enabling efficient state and data management across applications.
- Energetic team player and fast learner with the ability to work independently and deliver in fast-paced environments.
Overview
10
10
years of professional experience
Work History
Software Engineer
Paypal
San Jose, USA
03.2024 - Current
- Designed and developed backend services using Node.js, supporting scalable features for the PayPal Assistant platform.
- Built and integrated GraphQL APIs for efficient data fetching, enabling flexible and optimized client-server communication.
- Designed GraphQL schemas, resolvers, and queries to support real-time messaging and chatbot workflows.
- Improved API performance by optimizing resolver logic, reducing over-fetching, and implementing efficient data handling patterns.
- Implemented backend logic and middleware to handle authentication, request validation, and error handling.
- Collaborated with frontend teams to align GraphQL contracts and ensure seamless integration with React-based clients.
- Wrote comprehensive unit and integration tests for backend services, improving system reliability and coverage.
- Developed and executed end-to-end tests (Playwright) to validate full-stack workflows across API and UI layers.
- Monitored production systems using logs and metrics to debug API issues, optimize performance, and ensure system stability.
- Participated in Agile development cycles, working closely with cross-functional teams to deliver scalable backend solutions and support production deployments.
Software Engineer
Walmart Global Tech
Sunnyvale, USA
10.2023 - 02.2024
- Contributed to the Emerging Tech team to build a scalable online shopping platform with social-sharing and AI-driven capabilities.
- Developed backend services using Node.js, supporting core application logic and data processing for the MVP platform.
- Designed and implemented GraphQL APIs, including queries and mutations, to enable efficient communication between frontend and backend systems.
- Defined and structured GraphQL schemas and resolvers to support e-commerce workflows such as product interactions, user actions, and social features.
- Optimized GraphQL query performance by reducing over-fetching and improving resolver efficiency for faster data retrieval.
- Implemented backend logic for handling asynchronous data flows, ensuring reliable and consistent communication with databases and services.
- Collaborated with frontend engineers to define GraphQL contracts and ensure seamless integration with Next.js and React applications.
- Monitored and debugged production issues using Splunk logs, identifying bottlenecks and improving system stability.
- Wrote and improved unit and integration tests for backend services, achieving high coverage and ensuring robust API reliability.
- Participated in end-to-end deployment workflows, including production releases and rollback strategies, ensuring stable and reliable system operations.
Full Stack Developer
Paypal
Sunnyvale, USA
06.2022 - 10.2022
- Involved in the Users and Permissions Platform identity team to build and maintain server-side requests based on the different high priority projects.
- Utilize JavaScript, Node.JS, React and GraphQL queries to resolve different API requests.
- Used WebStorm as main development environment to maintain our code-base and making code changes based on requirement.
- Involved in code review for Github pull requests for code changes.
- Used Jupyter and SQL query to retrieve production account information to help clarify bug issues.
- Troubleshoot and debug GraphQL API issues for our user identity for different clients.
- Experienced with both React and GraphQL implementation process in production.
- Experienced with adding new property to GraphQL schema, updating query and mutation.
- Experienced with different user Auth includes user account, username with password identity and security content used GraphQL API.
- Involved in unit testing and functional testing for all the developed code included both React component and back-end testing.
- Monitor GraphQL API performance and optimize as needed.
- Collaborated with other teams for bug fixing, user data monitoring, and used Postman for testing requests.
- Participate in meetings with clients to discuss new features, and business logic.
- Used JIRA platform to track our epic, story and bug issues.
Software Engineer
Western Union
San Francisco, USA
06.2021 - 04.2022
- Contributed to the redesign and refactoring of a customer management system, focusing on optimizing the money transaction flow within a team of six engineers.
- Developed and maintained backend services using Node.js and Express.js, enabling scalable and efficient transaction processing.
- Designed and implemented RESTful APIs to handle transaction workflows, user data, and currency exchange operations.
- Built API endpoints for creating, retrieving, and managing transaction history, integrating with MongoDB and SQL databases.
- Implemented asynchronous data processing using async/await, ensuring reliable communication between backend services and databases.
- Integrated third-party APIs for real-time currency exchange rates, enhancing accuracy and functionality of transaction flows.
- Designed backend validation and error-handling mechanisms to ensure data integrity and secure transaction processing.
- Optimized database queries (SQL and NoSQL), improving system performance, reducing latency, and lowering operational costs.
- Monitored and debugged backend services to identify bottlenecks and ensure high availability under concurrent user requests.
- Collaborated with frontend and UI/UX teams to define API contracts and support seamless integration in an Agile Scrum environment.
Software Engineer
Volvo
San Jose, USA
02.2019 - 05.2020
- Contributed to redesigning and enhancing a Volvo car web platform, focusing on product categorization and user experience improvements.
- Developed responsive and interactive user interfaces using React, JavaScript, HTML5, and CSS3, improving usability and engagement.
- Built and integrated reusable frontend components to support dynamic product listings and filtering features (e.g., price, availability).
- Designed and consumed RESTful APIs to fetch and manage product data, enabling seamless communication between frontend and backend.
- Developed backend services using Node.js and Express.js, handling product categorization, inventory updates, and data retrieval.
- Integrated SQL and MongoDB databases, enabling efficient storage, querying, and transformation of product and availability data.
- Implemented filtering and search functionalities on both frontend and backend to optimize performance and reduce unnecessary data processing.
- Built pricing and loan calculation logic, supporting dynamic financial computations for vehicle purchases.
- Improved application performance by optimizing JavaScript logic, reducing DOM operations, and leveraging efficient data handling patterns.
- Collaborated with UI/UX designers and cross-functional teams in an Agile environment, participating in code reviews, testing, and deployment workflows.
Web developer Internship
Antino Labs
San Diego, USA
01.2017 - 12.2017
- The project is about building a company's goods management application that updates the information and quantities of all goods.
- Design and implement the goods management web application flow using JavaScript, HTML5 and CSS3.
- Use JavaScript and NoSQL MongoDB database to store data entered from web pages to record product information.
- Create a management application to update the inventory numbers for all items.
- The quantity purchased by the customer service will be transmitted to the database through JavaScript, then the quantity in the database will be modified, and finally the remaining goods will be updated on the web page.
- Use JavaScript to get the stock quantity of the item in the database to verify if it is enough to satisfy the customer's purchase.
- Hands on experience in interacts with JavaScript, and NoSQL MongoDB database.
- Knowledge of SQL querying language, data modeling and normalization.
- Involved in unit testing all the features and developed code.
- Monitoring website performance and rectifying front-end-related issues.
- This is a B2B marketing company.
Business Data Analyst Internship
ViVi
San Diego, USA
02.2016 - 09.2016
- Integrated and mine large sales data sets, connecting data from various system sources to identify critical insights and sales data solutions.
- Utilized data mining and statistical techniques to derive business value from shop, product, financial, and customer transaction data.
- Designed and created analysis and reports that include summaries, graphs, diagrams, and other visual representations in Python or Excel.
Education
Bachelor of Science - Mathematics & Computer Science
University of California San Diego
San Diego, CAMaster of Science - Computer Systems And Engineering
California Science And Technology University
Milpitas, CASkills
- Python
- SQL
- JavaScript
- React
- Redux
- MongoDB
- JSON
- Node
- Bootstrap
- VSCode
- GIT
- Jira
- Figma
- GraphQL
- Zustand
- Playwright
Timeline
Software Engineer
Paypal
03.2024 - Current
Software Engineer
Walmart Global Tech
10.2023 - 02.2024
Full Stack Developer
Paypal
06.2022 - 10.2022
Software Engineer
Western Union
06.2021 - 04.2022
Software Engineer
Volvo
02.2019 - 05.2020
Web developer Internship
Antino Labs
01.2017 - 12.2017
Business Data Analyst Internship
ViVi
02.2016 - 09.2016
Bachelor of Science - Mathematics & Computer Science
University of California San Diego
Master of Science - Computer Systems And Engineering
California Science And Technology University