PhyongNam is available for hire
Hire PhyongNamPhyongNam Kim
Verified Expert in Engineering
Full-stack Developer
Milwaukee, WI, United States
Toptal member since September 19, 2019
Bio
Kim is an accomplished front-end developer with some back-end experience who is committed to building outstanding websites and mobile apps. With his expertise in React, React Native, Vue, and other technologies, he creates visually stunning, user-friendly, secure, and performant experiences. Kim's impressive track record includes developing large-scale projects from scratch, updating existing ones to ensure high quality, and enhancing them with new features and pages.
Portfolio
Hover
HTML5, CSS3, JavaScript, ECMAScript (ES6), React, TypeScript, Storybook...
GeneDx
React, TypeScript, Gatsby, Storybook, SCSS, Tailwind CSS, React Testing Library...
Tellimer
Vue, Nuxt.js, Vuex, TypeScript, Storybook, GraphQL, SCSS, Bootstrap, Jest...
Experience
- Front-end Development - 10 years
- React - 6 years
- Unit Testing - 4 years
- Mobile App Development - 3 years
- React Native - 3 years
- Vue - 2 years
- E2E Testing - 2 years
- Node.js - 2 years
Availability
Full-time
Preferred Environment
Git, Visual Studio Code (VS Code), MacOS
The most amazing...
...thing I've coded was a collaboration app for remote teams, which has been adopted by renowned companies such as Alaska Airlines, Delta Air Lines, KFC, and more.
Work Experience
Senior Front-end Developer
2023 - 2025
Hover
- Developed a design system in React using Storybook, replacing 200+ legacy components across multiple websites, enhancing UI consistency and development efficiency.
- Rebuilt the company website with Next.js, improving page load speed by 40% and increasing monthly visitors by 30%.
- Implemented WCAG 2.0 accessibility standards across design system components, improving the user experience for all users.
- Delivered high-quality, pixel-perfect, responsive UIs based on Figma designs in close collaboration with designers.
- Developed unit and end-to-end testing to ensure robust functionality and reliability of components and websites.
- Implemented A/B testing and used monitoring tools to optimize performance and enhance UI/UX.
- Collaborated with cross-functional teams to clarify requirements, discuss feasibility, and ensure seamless front-end implementation.
Technologies: HTML5, CSS3, JavaScript, ECMAScript (ES6), React, TypeScript, Storybook, Chakra UI, Contentful, Segment.io, OneSignal, HubSpot, Design Systems, Web Accessibility, Next.js
Senior React Front-end Developer
2021 - 2023
GeneDx
- Developed React UI components for company-wide design systems ensuring consistency and enhancing the user experience.
- Migrated legacy AngularJS 1.6 code to React 18 incrementally, converting pages individually and managing routing.
- Made minor updates and fixes to the existing C# .NET back end.
- Maintained legacy AngularJS 1.6 code and a WordPress website.
Technologies: React, TypeScript, Gatsby, Storybook, SCSS, Tailwind CSS, React Testing Library, Angular, WordPress, PHP, C#, .NET, CI/CD Pipelines, Unit Testing, Front-end Development, Full-stack Development
Senior Vue Front-end Developer
2019 - 2021
Tellimer
- Redesigned a SaaS platform using Vue.js, delivering pixel-perfect, responsive UIs, optimizing performance, resulting in a 100%+ increase in registered companies and users.
- Developed the front-end and back-end of an AI-powered data extraction tool with AWS Amplify, Lambda, API Gateway, and other AWS services, ensuring scalability and efficiency.
- Developed email templates for the marketing team and integrated them with Mailchimp.
- Demonstrated strong learning ability by quickly mastering new technologies, ensuring efficient and effective project delivery.
Technologies: Vue, Nuxt.js, Vuex, TypeScript, Storybook, GraphQL, SCSS, Bootstrap, Jest, Cypress, LaunchDarkly, Litmus, Mailchimp, Amazon Web Services (AWS), GitLab CI/CD, Unit Testing, E2E Testing, A/B Testing, Serverless Architecture, Front-end Development
Senior React/React Native Developer
2017 - 2019
Springshot
- Built a React Native app for iOS and Android, adopted by major brands like KFC, Alaska Airlines, and Delta Airlines, driving operational efficiency.
- Developed a high-availability, scalable website and admin dashboard in React for scheduling, mission management, and notifications.
- Integrated Azure AD B2C, Firebase services, REST APIs, and GraphQL to improve security, optimize performance, enable real-time messaging, and enhance app functionality.
- Implemented unit and end-to-end test scripts using TDD, integrated into a CI/CD pipeline with Jenkins.
- Worked in an agile and fast-paced environment, collaborating with cross-functional teams to align technical development with business objectives.
Technologies: React Native, React, GraphQL, Material UI, Jest, Appium, Xcode, Android Studio, Socket.IO, Firebase, Azure Active Directory B2C (ADB2C), Jenkins, Fastlane, Unit Testing, E2E Testing, Test-driven Development (TDD), Front-end Development, Mobile App Development
Senior Full Stack Developer
2014 - 2017
NHN Entertainment
- Built a scalable SaaS platform from scratch with React and Node.js, supporting millions of monthly active users (MAUs) with high performance.
- Launched an MVP for a youth content platform, driving rapid growth to millions of users across South Asia.
- Managed multiple high-priority projects simultaneously, delivering them on time while maintaining high-quality standards.
- Developed clean, maintainable, and well-documented code to ensure long-term scalability and ease of collaboration.
- Collaborated with non-technical clients and stakeholders, translating complex technical concepts into actionable insights.
- Promoted to Senior Developer for consistently delivering high-quality code, improving performance, scalability, and best practices.
Technologies: React, Material UI, Node.js, Express.js, MongoDB, WebSockets, REST APIs, Payment Gateways, Full-stack Development, Minimum Viable Product (MVP), PostgreSQL, Redux, HTML, CSS, MySQL, D3.js
Experience
Component Library for a Design System
https://storybook.hover.toI worked as a senior front-end developer and developed components for the design system, which is used across various websites developed and utilized by the company. We focused a lot on supporting accessibility.
Mobile App to Manage and Track Remote Teams
https://apps.apple.com/app/id1315795000An app that enables remote teams to coordinate and perform time-sensitive tasks quickly and efficiently, used by renowned enterprises such as KFC, Alaska Airlines, and Delta Air Lines.
I worked as a senior React Native developer in a mobile team, collaborating with both team members and cross-functional teams. I developed critical features, including single sign-on (SSO), offline-supported news bulletins, push notifications, live chat, and Beacon signal detection.
We utilized TDD to build a high-quality app.
I worked as a senior React Native developer in a mobile team, collaborating with both team members and cross-functional teams. I developed critical features, including single sign-on (SSO), offline-supported news bulletins, push notifications, live chat, and Beacon signal detection.
We utilized TDD to build a high-quality app.
Admin Dashboard for Remote Team Management and Tracking Platform
https://webapp.springshot.comAn admin dashboard for the platform is used to manage and track remote teams, and I worked as a senior front-end developer on a dashboard project, focusing on developing the SSO and mission scheduling system.
This dashboard is for the Springshot platform, which is utilized by large companies such as KFC, Alaska Airlines, Delta Air Lines, and others.
This dashboard is for the Springshot platform, which is utilized by large companies such as KFC, Alaska Airlines, Delta Air Lines, and others.
Business Insight News Platform
https://tellimer.comA business insight news platform similar to Bloomberg. I was a senior Vue.js front-end developer, contributing to the news website and admin dashboard.
My responsibilities included optimizing performance, updating web pages to match new designs, adding new pages with A/B testing, developing email templates, etc.
My responsibilities included optimizing performance, updating web pages to match new designs, adding new pages with A/B testing, developing email templates, etc.
MVP for a Fleet-based Car-sharing Mobile App
I worked on developing the MVP iOS and Android app for a fleet-based car-sharing platform. This app played a crucial role in helping the company secure funding and expand its operations.
The app is now one of the top car-sharing apps in Korea.
The app is now one of the top car-sharing apps in Korea.
Website and Admin Dashboard for Fleet-based Car-sharing Platform
https://www.socar.krA website and admin dashboard for one of the top car-sharing platforms in Korea. I worked as a full-stack developer and developed the feedback system, payment system, and support system for both the website and admin dashboard.
Social Community and Membership Platform
A membership platform that empowers content creators to run subscription services by providing comprehensive business tools. I worked as a senior React developer and developed onboarding pages, a creator's dashboard, and some global UI components.
Website for Document Analyzing AI Service
https://parsel.aiA website with a membership that provides services to analyze documents using AI.
As the sole front-end developer in this project, I owned all front-end development tasks, from architecture design and language/framework selection to deployment and testing.
As the sole front-end developer in this project, I owned all front-end development tasks, from architecture design and language/framework selection to deployment and testing.
Education
2010 - 2014
Bachelor's Degree in Computer Science
Southeastern University - Washington, D.C.
Certifications
JANUARY 2012 - JANUARY 2015
TOEIC
Toeic
SEPTEMBER 2011 - PRESENT
Business English Certificate
Cambridge English
APRIL 2011 - PRESENT
Project+
CompTIA
MARCH 2011 - MARCH 2014
Security+
CompTIA
Skills
Libraries/APIs
React, Vue, Vuex, React Testing Library, REST APIs, Node.js, jQuery, Socket.IO, Stripe, D3.js, Segment.io
Tools
LaunchDarkly, Litmus, Mailchimp, Azure Active Directory B2C (ADB2C), Xcode, Android Studio, GitLab CI/CD, Jenkins, Fastlane, OneSignal
Languages
TypeScript, GraphQL, SCSS, Sass, HTML, CSS, JavaScript, PHP, C#, HTML5, CSS3, ECMAScript (ES6)
Frameworks
React Native, Next.js, Nuxt.js, Tailwind CSS, Material UI, Bootstrap, Redux, Jest, Cypress, Appium, Express.js, Angular, .NET
Paradigms
Unit Testing, E2E Testing, Test-driven Development (TDD), Serverless Architecture
Platforms
GreenSock Animation Platform (GSAP), Firebase, Amazon Web Services (AWS), Eclipse, WordPress, Contentful, HubSpot
Storage
PostgreSQL, MySQL, MongoDB
Other
Gatsby, Storybook, Chakra UI, Front-end Development, Design Systems, A/B Testing, Mobile App Development, iOS App Development, Android App Development, Maps, Geolocation, IAP SDK, Minimum Viable Product (MVP), Payment Gateways, RESTful Microservices, WebSockets, CI/CD Pipelines, Full-stack Development, Web Accessibility, Software Development
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