Marcus Hsu, Developer in Bellevue, United States
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Marcus Hsu

Verified Expert  in Engineering

Full-stack Developer

Location
Bellevue, United States
Toptal Member Since
May 19, 2020

Marcus has over a decade of experience in front-end development, building React websites and developing iOS and Android apps in React Native for the past several years. He has helped at least 31 enterprises and startup clients to design and build high-quality cross-platform apps using React, React Native, and Node.js. Marcus has also built enterprise-scale apps that have impacted over 30 million users in 140 countries.

Front-endSaaSWeb App DevelopmentWeb DevelopmentSoftwareResponsive UIFull-stackMobile App DevelopmentMobile ApplicationsMobile UICTOCSSCSS3REST APIsNode.js

Portfolio

A Residential Brokerage Company
React, Redux, User Experience (UX), User Interface (UI), Performance, SCSS...
A Real Estate Platform Provider
React, React Native, Amazon Web Services (AWS), Styled-components...
A State University Technology Office
React, React Native, D3.js, React Redux Form, Formik, Redux-Saga, Redux, OAuth...

Experience

JavaScript - 10 yearsNode.js - 8 yearsReact - 7 yearsReact Native - 6 yearsJest - 6 yearsRedux - 6 yearsTypeScript - 4 yearsSass - 4 years

Availability

Full-time

Preferred Environment

Node.js, Redux, Sass, JavaScript, React, React Native, TypeScript, Jest, Cross-platform, Web & Mobile Applications

The most amazing...

...projects I've built from scratch using React and React Native are enterprise-scale web and mobile apps that impact over 30 million users in 140 countries.

Work Experience

Hands-on Tech Lead

2021 - PRESENT
A Residential Brokerage Company
  • Led a team of front- and back-end developers to spearhead the technical direction for the luxury bidding platform's minimum viable product.
  • Cooperated constantly with the PM and UX designer to make high-level architectural decisions and led design meetings, making most of the final technical decisions.
  • Performed hands-on coding daily to accomplish the client's urgent requests and critical bug fixes and guided each junior developer to ensure the team met every sprint deadline.
  • Mentored junior developers regarding their code and approach to solving problems.
  • Reviewed every pull request in great detail before merging into the codebase to ensure the highest code quality at all times.
  • Engaged in solely maintaining the codebase after product launch as I deeply understood how each piece of code functions for 90% of the entire codebase.
  • Accomplished several critical bug fixes, UX improvements, and new large features.
Technologies: React, Redux, User Experience (UX), User Interface (UI), Performance, SCSS, HTML, Functional Programming, JavaScript, TypeScript, CSS, CSS3, HTML5, React Redux, Formik, Agile Software Development, Front-end, APIs, RESTful Microservices, Webpack, ECMAScript (ES6), ES7, ES8, Single-page Applications (SPA), Unit Testing, Agile, Scrum, Jira, SaaS, Architecture, App Development, Web Development, Sass, Software Architecture, Responsive Layout, Responsive Web Apps, NPM, Figma, Zeplin, InVision, React Router, TypeScript 3, Software, REST APIs, Computer Science, Flux, Responsive UI, Web Applications, Jest

Tech Lead

2021 - 2022
A Real Estate Platform Provider
  • Led a newly-found design system team to spearhead its technical direction and provided consultation for several application teams.
  • Assessed the current codebase and devised strategies to incorporate the new design system into the existing apps.
  • Developed a centralized reusable component library from scratch, providing a set of standards to guide its usage. It increased the productivity of application teams to focus on business logic without building their own components.
  • Drove the adoption of the centralized reusable component library to be consumed by several React and React Native applications. It involved countless conflict resolution, migration, testing, and bug fixes before releasing each app back to production.
  • Pioneered a way to build and run the React Native components' Storybook on iOS and Android devices and any web browser, as there was no existing solution. It enabled the components to be built once and used everywhere.
  • Set up a comprehensive unit test framework to test most kinds of user interactions on mobile devices and stimulated a native mobile environment where the framework would run. It was built with Jest, a testing library, and several others.
  • Created a design tokens build system from scratch to allow developers to style once and consume it on any platform. It became a single place to create or edit reusable style guides and assets, making the styles consistent across different apps.
  • Built a library to handle the responsiveness of mobile devices since there is no out-of-the-box solution in React Native to set the breakpoints like media queries on the web.
Technologies: React, React Native, Amazon Web Services (AWS), Styled-components, MUI (Material UI), React Native for Web, React Native Bridge, Functional Programming, JavaScript, TypeScript, Mobile App Development, User Interface (UI), User Experience (UX), Agile Software Development, iOS, Android, Front-end, Mobile Applications, Mobile Development, AWS CodePipeline, APIs, Webpack, ECMAScript (ES6), ES7, ES8, Unit Testing, Jest, Agile, Scrum, Jira, SaaS, Architecture, Technical Consulting, Web Consulting, App Development, Web Development, Cloud, Mobile Apps, Web & Mobile Applications, Software Architecture, Zeplin, Figma, Responsive Layout, Responsive Web Apps, NPM, TypeScript 3, Linux, Cross-platform, Cross-platform Testing, Software, Mobile UI, Computer Science, Responsive UI, Cross-platform App Development, Mobile, Web Applications, Monorepos

Senior React Native and React Engineer

2021 - 2021
A State University Technology Office
  • Built an Android app to manage self-sovereign identity using blockchain technology. It uses complex native modules to connect to each user's wallet on the blockchain and was built with React Native, TypeScript, D3.js, Hyperledger Aries, and Indy SDK.
  • Developed an admin console—solely from scratch to product launch—to manage identities and credentials on the blockchain. It has complex charts, graphs, and animation for data visualization and is built with React, TypeScript, and Material UI.
  • Architected and implemented the admin console application's internationalization and localization features to make it available to all the supported countries.
Technologies: React, React Native, D3.js, React Redux Form, Formik, Redux-Saga, Redux, OAuth, OAuth 2, Cross-platform, Cross-platform App Development, React Native Bridge, Jest, User Experience (UX), User Interface (UI), SCSS, HTML, Functional Programming, JavaScript, TypeScript, Styled-components, MUI (Material UI), CSS, CSS3, HTML5, React Redux, Mobile App Development, Agile Software Development, iOS, Android, Front-end, Mobile Applications, Mobile Development, Webpack, ECMAScript (ES6), ES7, ES8, Single-page Applications (SPA), Agile, Scrum, Jira, SaaS, Architecture, App Development, Web Development, Sass, Software Architecture, Responsive Layout, Responsive Web Apps, NPM, Figma, Zeplin, Linux, Web & Mobile Applications, TypeScript 3, React Router, Software, Mobile UI, Mobile, Computer Science, Flux, Responsive UI, Web Applications

Top Full-stack Developer

2021 - 2021
A Healthcare Staffing Technology Platform
  • Engaged as the main contributor to Android mobile apps, impacting 350,000+ nurses by enabling them to log their times easily. It involved complicated photo taking, scanning, and identity verification and was built with React Native and TypeScript.
  • Completed several painful migrations of native modules to make an existing sophisticated Android app cross-platform so it could work and be developed on iOS and Android in a single codebase.
  • Drove the front- and back-end development of real-time geolocation tracking. It involved background location-tracking and geofencing with battery-conscious motion-detection intelligence for iOS and Android using React Native and the Google Maps API.
  • Set up the complicated build, deployment, beta testing, release, and code signing processes on the App Store and Google Play Store for several different environment settings.
Technologies: JavaScript, Redux, React Native, Cross-platform, Cross-platform App Development, React Native Bridge, User Experience (UX), User Interface (UI), Functional Programming, TypeScript, Redux-Saga, Styled-components, MUI (Material UI), React Redux, Mobile App Development, Agile Software Development, iOS, Android, Front-end, Mobile Applications, Mobile Development, Webpack, ECMAScript (ES6), ES7, ES8, Unit Testing, Agile, Scrum, Jira, SaaS, Architecture, App Development, Mobile Apps, Software Architecture, Responsive Layout, NPM, Figma, TypeScript 3, Zeplin, Linux, Software, Mobile UI, Mobile, Computer Science, Flux, Responsive UI, Jest

Senior React Native and React Developer

2020 - 2021
A Healthcare Digital Platform Provider
  • Used React Native, React Native for Web, and TypeScript to build an iPad application to connect patients, doctors, and health plans seamlessly. It later extended its capability to have cross-platform support, such as web and Android tablets.
  • Developed solely and from scratch to product launch a healthcare app related to PIP diabetes, which impacted 800,000+ users. It was built with React and TypeScript.
  • Implemented a proof of concept to experiment with different trending technologies and fancy user experiences, such as a flowchart, to spearhead the next generation of healthcare software.
  • Built several other healthcare cross-platform applications to enable data-driven insights for patients, doctors, and administrators, leveraging artificial intelligence and machine learning technology.
Technologies: Amazon Web Services (AWS), Amazon Cognito, OAuth, SCSS, React, React Native, HTML, Functional Programming, JavaScript, TypeScript, Redux, Styled-components, MUI (Material UI), CSS, CSS3, HTML5, React Redux, Mobile App Development, User Interface (UI), User Experience (UX), Agile Software Development, iOS, Android, Front-end, Mobile Applications, Mobile Development, GraphDB, Docker, Amazon S3 (AWS S3), APIs, RESTful Microservices, Webpack, ECMAScript (ES6), ES7, ES8, Single-page Applications (SPA), Unit Testing, Agile, Scrum, Jira, SaaS, Architecture, App Development, Web Development, Cloud, Mobile Apps, Web App Development, Sass, Software Architecture, Responsive Layout, Responsive Web Apps, NPM, Figma, React Router, TypeScript 3, Web & Mobile Applications, Zeplin, Linux, Cross-platform, Software, Mobile UI, Redux-Saga, REST APIs, Mobile, Computer Science, Flux, Responsive UI, Web Applications, OAuth 2, React Native for Web, React Native Bridge, Cross-platform App Development, Jest, Monorepos

Senior Front-end Software Engineer

2016 - 2020
ADP Innovation Lab
  • Led the front-end development of the new user onboarding and account setup workflows for both web and mobile, which impacted 30+ million users. It is built with React and React Native.
  • Spearheaded the front-end development of the internationalization support for all client-critical pages to make the ADP website available in 140+ countries.
  • Served as the tech lead of a team of more than ten engineers in building a new identity control center platform for both web and mobile, which impacted over 20,000 users. It was built with React, React Native, Node.js, MySQL, and Couchbase.
  • Led the development of a new multi-factor authentication framework along with spearheading the framework adoption initiative across multiple product teams to make it available in all ADP's core products for 15,000+ companies' payrolls worldwide.
  • Onboarded, trained, and mentored 10+ junior-, mid-, and senior-level developers who joined my team and had them follow JavaScript, React, Redux, and Sass best coding practices.
  • Contributed to product and roadmap planning and UX design sessions with product managers, clients, and UX designers.
  • Achieved a proven track record that has allowed me to step up and manage the team from time to time to meet critical product deadlines, even when faced with minimal developer resources.
  • Took full responsibility and ownership of the codebase of client-critical identity-related front-end workflows; became the main point of contact and stayed on call for any production issues, feature requests, and support.
  • Demonstrated and frequently presented the status of the development I have been leading and the results of my research at leadership conferences.
Technologies: Amazon Web Services (AWS), SCSS, HTML, JavaScript, MongoDB, MySQL, Node.js, Redux, React Native, React, CSS, CSS3, HTML5, React Redux, Mobile App Development, Jest, NoSQL, Bootstrap, Web App Development, User Interface (UI), User Experience (UX), Agile Software Development, iOS, Android, Front-end, Mobile Applications, Mobile Development, GraphDB, Selenium, Docker, Amazon S3 (AWS S3), WebdriverIO, APIs, RESTful Microservices, Webpack, Jenkins Pipeline, ECMAScript (ES6), ES7, ES8, SQL, Single-page Applications (SPA), Unit Testing, Agile, Scrum, Jira, SaaS, Leadership, Architecture, App Development, TypeScript, API Applications, Web Architecture, Web Development, Cloud, Mobile Apps, Web App Deployment, Sass, Technical Leadership, Software Architecture, Responsive Layout, Responsive Web Apps, NPM, Figma, MUI (Material UI), Styled-components, React Router, TypeScript 3, Web & Mobile Applications, Zeplin, Linux, Cross-platform, Software, Mobile UI, Redux-Saga, Functional Programming, REST APIs, Mobile, Containers, Minimum Viable Product (MVP), Engineering, Computer Science, Flux, Responsive UI, Web Applications, Sequelize, Cross-platform App Development, React Native Bridge, Performance, Monorepos

Full-stack Software Engineer

2015 - 2016
ADP
  • Architected and designed a proprietary authentication and authorization framework for web and mobile applications. The framework contains three granted patents with my name on all of them.
  • Worked with 20 developers to complete the development of the proprietary authorization framework using React, Node.js, MongoDB, MySQL, Scala, and Casandra.
  • Designed and developed a Selenium end-to-end regression test framework to replace manual tests companywide. Ensured the framework covered not only all the common use cases and edge cases but all major browsers, as well as IE and IE Edge.
  • Ensured 100% unit testing code coverage for all major front- and back-end repositories using Jest, Mocha, and Chai.
  • Rolled out a database migration to switch from MongoDB to Couchbase Server for all the microservices in the team.
  • Adhered to the highest security standards for front- and back-end development, contributing to ADP's ranking as 1st on the Security 500.
  • Executed in a highly experimental and R&D-oriented domain to stay on the cutting edge of trending open-source technologies.
  • Guaranteed each release's quality and continuous deployment by automating the building process and comprehensive regression testing in Jenkins.
  • Worked closely with the infrastructure team to constantly update and patch all applications and microservices so that the team could stay up to date with new technology stacks and security requirements and achieve stronger performance.
  • Secured integration tests covered all the possible interactions between services and databases in a real-cloud environment.
Technologies: HTML, JavaScript, MongoDB, MySQL, Node.js, Redux, React, CSS, CSS3, HTML5, React Redux, Jest, NoSQL, Bootstrap, Web App Development, User Interface (UI), User Experience (UX), Agile Software Development, Front-end, GraphDB, Selenium, Docker, Amazon S3 (AWS S3), APIs, RESTful Microservices, Webpack, Jenkins Pipeline, ECMAScript (ES6), ES7, ES8, SQL, Single-page Applications (SPA), Unit Testing, Agile, Scrum, Jira, SaaS, App Development, API Applications, Web Development, Cloud, Web App Deployment, Software Architecture, Responsive Layout, Technical Leadership, Responsive Web Apps, React Native, NPM, Figma, MUI (Material UI), React Router, TypeScript 3, Web & Mobile Applications, Zeplin, Linux, Cross-platform, Software, Mobile UI, Functional Programming, REST APIs, Mobile, Containers, Minimum Viable Product (MVP), Engineering, Computer Science, Flux, Responsive UI, Web Applications, Leadership, Sequelize, Cross-platform App Development, React Native Bridge, Performance, Amazon Web Services (AWS), InVision, Monorepos

Full-stack Web Developer

2014 - 2015
Acupay
  • Developed solely and from scratch to launch a global asset management services web app with a monthly value of $500,000. It was built with AngularJS, Node.js, Express.js and Jade, Microsoft SQL Server, Grunt, and multi-factor authentication (MFA).
  • Built by myself and from scratch to launch a European tax-processing-services web app with a monthly value of $100,000. It was built with Angular, Node.js, Hapi.js, Handlebar.js, and Microsoft SQL Server.
  • Implemented a centralized mailing server to manage all internal email in a secure channel and provide an admin dashboard with real-time mailing status updates and stats charts. It was built with React, Flux, WebSockets, D3.js, and Grunt.
Technologies: Grunt, Flux, D3.js, WebSockets, Node.js, Microsoft SQL Server, JavaScript, React, ECMAScript (ES6), App Development, Front-end, Web App Development, API Applications, APIs, Bootstrap, CSS, SaaS, Single-page Applications (SPA), Cloud, Software Architecture, Responsive Layout, Responsive Web Apps, Redux, NPM, Figma, React Router, Web & Mobile Applications, Zeplin, Linux, Software, Functional Programming, REST APIs, Minimum Viable Product (MVP), Engineering, Computer Science, Responsive UI, Web Applications, Web Development, Sequelize, Banking & Finance, User Interface (UI), InVision

Teaching Assistant

2014 - 2014
Columbia University
  • Assisted the professor in supervising over 50 students concerning their big data programming projects using Hadoop 2, Pig, Mahout, GraphDB, Hive, HBase, and Oozie.
  • Offered support to guide and debug all course-related resources, assignments, and projects for over 100 students every week.
  • Hosted teaching assistant sessions for live demos to demonstrate how to build, run, and develop Pig, Hive, HBase, Oozie, Mahout, and GraphDB in a Hadoop 2 ecosystem and how to apply them to a real-world problem.
Technologies: GraphDB, Hadoop, Amazon Web Services (AWS), Amazon S3 (AWS S3), Cloud, Leadership, Software Architecture, Responsive Layout, Technical Leadership, Responsive Web Apps, NPM, Web & Mobile Applications, Linux, Software, REST APIs, Mobile, Engineering, Computer Science, Web App Development, Web Applications, Web Development, App Development, OAuth, OAuth 2, User Interface (UI)

Arthur Murray Official (iOS and Android)

https://arthurmurray.com/
The number one tool for competitive ballroom dancers.

It is built for the biggest ballroom dance studio franchise in the world. It uses React Native for the front end and Node.js and MySQL for back-end big data processing.

It's available for download in the App Store (Apple.co/2Ug9x66) and Play Store (Bit.ly/3duOERK).

Pinto (iOS and Android)

Pinto is the number one digitization platform that provides an efficient-and-smart way to record, upload, and track the ingredients of each product on the shelf for the largest retailers like Kroger.

It's built with React Native and GraphQL for the front end along with an integration with the existing back end.

It's available for download in the App Store (Apple.co/2Qz6VEj) and Play Store (Bit.ly/3ap7OGK).

Pacesetter (iOS)

A fitness application that trains athletes to control their pace in a marathon in real-time.

It's built with React Native for the front end as well as geolocation, motion tracking, and iTunes integration; Firebase for back-end data storage. It's currently in beta testing and will be available in the App Store very soon.

Get Apollo (iOS and Android)

https://www.getapollo.in/
The go-to app for real-time party information of your favorite clubs and bars at your fingertips.

It's built with React Native for the front end; Firebase for back-end storage, OAuth authentication, and app analytics.

It's available for download in the App Store (Apple.co/2Lh7oq3) and Play Store (Bit.ly/2WhuujG).

Circlus Connect (iOS)

A platform that uses influencers' voices to help locals find delicious restaurant deals.

It's built with React Native for the front end and Node.js, MongoDB, and Stripe API for back-end payment processing. It's available for download in the App Store (Aapple.co/2VGkTC3).

Local Detour (iOS)

A location-based service helps people to uncover off-the-beaten-path events.
It's built with React Native for the front end; Firebase for back-end data storage and OAuth authentication. It's available for download in the App Store (Apple.co/2VEdHX6).

Future Plans (iOS)

A life-and-financial planning platform to get your future covered.

It's built with React Native and Expo for front-end rapid prototyping. It's currently in beta testing and will be available in the App Store very soon.

Wonda Shop (iOS and Android)

A leading eCommerce platform to shop for food, cosmetics, apparel, electronics, and home goods.

It's built with React Native and Expo for front-end rapid prototyping. It's currently in beta testing and will be available in the App Store and Play Store very soon.

Goti (iOS and Android)

The first social media and marketplace platform customized exclusively for women.

It's built with React Native and Expo for front-end rapid prototyping. It's currently in beta testing and will be available in the App Store and Play Store very soon.

Lifion by ADP (Web)

I contributed to the build of an industry-leading payroll and HR management platform that has impacted over 30 million users in around 140 countries.

It's built with React, Redux, and several proprietary custom-built components.

Play Nice (Web)

https://staging.playniceapp.com/home
I contributed to the development of a platform to eliminate cyberbullying.

It's built with React for the front end and Node.js, MongoDB, Stripe API, Twillio API, Gmail API for the back end. Feel free to reach out for more details.

Taiwan Society for Risk Analysis (Web)

I contributed to the development of an international academic platform.

It's built with React for the front end and Node.js, MongoDB, Firebase for back-end data storage. Feel free to reach out for more details about the project.

Sugarpost (Web)

I contributed to the development of a construction management platform.

It's built with Angular for the front end and Node.js and MongoDB for back-end big data processing. Feel free to reach out for more details about the project.

CMTech (Web)

I contributed to the development of this construction management platform.

It's built with Angular for the front end and Node.js and MongoDB for back-end big data processing. Feel free to reach out for more details about this project.

Source Code for a React Native App

https://github.com/kiddkevin00/get-apollo
I developed this code structure for one of my startup clients. It's built with React Native and Redux. It's the source code for the Get Apollo app in the App Store (Apple.co/2Lh7oq3) and will be in the Play Store soon (Getapollo.in).

Source Code for a React App (Full-stack)

https://github.com/kiddkevin00/top-times
I architected this code structure for a React web app and its back-end server. It is built with React, Redux, Sass, and Jest for the front end and Node.js, MongoDB, PostgreSQL, Mocha, and JWT for the back end.

Languages

SCSS, ES7, JavaScript, HTML5, CSS, HTML, Sass, ECMAScript (ES6), ES8, TypeScript, CSS3, TypeScript 3, GraphQL, SQL

Frameworks

React Native, Jest, Redux, Flux, JSON Web Tokens (JWT), MUI (Material UI), OAuth 2, Bootstrap, Selenium, Hadoop

Libraries/APIs

React, Node.js, React Redux, REST APIs, Redux-Saga, React Router, React Redux Form, Formik, React Native for Web, D3.js, Stripe API, Stripe Connect API, Jenkins Pipeline

Tools

WebdriverIO, Webpack, Expo, Expo.io, Jira, ExpoKit, Mocha, NPM, Sequelize, Figma, Zeplin, Amazon Cognito, Grunt, InVision

Paradigms

Agile Software Development, Mobile Development, Unit Testing, Agile, Scrum, App Development, Web Architecture, Responsive Layout, Functional Programming, Cross-platform

Platforms

Firebase, Docker, Mobile, Linux, iOS, Android, Amazon Web Services (AWS)

Storage

MongoDB, MySQL, Microsoft SQL Server, PostgreSQL, NoSQL, Amazon S3 (AWS S3)

Other

RESTful Microservices, Mobile App Development, Web App Deployment, Mobile Applications, APIs, Front-end, User Experience (UX), User Interface (UI), Full-stack, NativeBase, Single-page Applications (SPA), SaaS, Architecture, Web App Development, API Applications, Web Development, Cloud, Mobile Apps, Web Applications, Responsive UI, Computer Science, Engineering, Software Architecture, Responsive Web Apps, Minimum Viable Product (MVP), Containers, Consulting, Technical Consulting, Web Consulting, CTO, Mobile UI, Software, Styled-components, Web & Mobile Applications, Cross-platform Testing, Cross-platform App Development, Performance, Monorepos, Mobile Payments, Stripe Payments, Leadership, Geolocation, Airtable, Technical Leadership, OAuth, React Native Bridge, AWS CodePipeline, WebSockets, GraphDB, Electrical Engineering

Industry Expertise

Banking & Finance

2013 - 2014

Master's Degree in Electrical Engineering, specializing in Computer Science

Columbia University - New York, United States

2009 - 2012

Bachelor of Science Degree in Engineering Science, specializing in Computer Science

National Taiwan University - Taipei, Taiwan