Rumen Han, React & Django Developer in Hong Kong, Hong Kong
Rumen Han

React & Django Developer in Hong Kong, Hong Kong

Member since October 25, 2018
Rumen has eight years of experience in web development using JavaScript (React, Angular), Python (Django), and AWS. He has worked on a variety of projects at companies of all sizes. He has been an important problem solver in the teams and never failed to deliver quality work with his hard work and problem-solving skills. Rumen really cares about user-friendliness and the performance of your application.
Rumen is now available for hire




Hong Kong, Hong Kong



Preferred Environment

Mac OS, Windows 10, VS Code, Atom

The most amazing...

...thing I've contributed to is the three.js project with React and Next.JS. I used a lot of algorithms and proper data structures to speed up 3D model rendering.


  • Senior Full-stack Developer

    2020 - PRESENT
    Care Of (via Toptal)
    • Developed a Quora-like site using React, React-Hook front-end with GraphQL for a home-care service company based in Australia.
    • Implemented mobile-responsive front-end pages with React, Bootstrap, and SCSS.
    • Used Apollo-boost to consume GraphQL API.
    • Engaged back-end development in Nest.js and PostgreSQL.
    • Integrated third-party APIs like Sendgrid.
    Technologies: React, Apollo Boost, Nest.js, Bootstrap, SCSS, Node.js, Sendgrid, Postgres, GraphQL
  • Full-stack JavaScript Expert

    2019 - 2019
    Roubler Pte Ltd (via Toptal)
    • Developed USA’s leading cloud-based workforce management, HR, and payroll software with Angular, Node.js, Express.js, GraphQL, Apollo, PostgreSQL, Bootstrap, etc.
    • Worked closely with web development and software design team for production, modification, and maintenance of web applications.
    • Developed and unit-tested software that meets business requirements and technical design. And Maintained code coverage quality for all new components built close to 90% with an emphasis on TDD.
    • Built great looking with technologies like Bootstrap to the dynamic back end in
    • Troubleshot pre- and post-production implementations.
    Technologies: Angular, Node.js, Express.js, GraphQL, Apollo, PostgreSQL, Bootstrap, CypressJS, RxJS, AWS-Lambda, React Native
  • React, Node.js Developer

    2019 - 2019
    TRM Labs (via Toptal)
    • Joined the team as a React and Node.js developer with cryptocurrency experience.
    • Implemented React High-Order-Components along with AntD.
    • Implemented REST APIs with Feathers.JS.
    • Wrote Blockchain-related helper functions.
    • Worked on the styling of React components along with Styled-Component.
    • Used Enzyme, Jest, and Chai for the test and Lerna for packaging resources.
    Technologies: React, Redux-Saga, Reselect, Node.js, Feathers.js, AntD, Docker, Postgres, MongoDB, Blockchain, Ethereum, Bitcoin
  • Remote Full-stack Developer

    2019 - 2019
    • Worked on Boston hospitals' medication provider search project focusing on fixing issues and implementing new features both front-end and back-end.
    • Implemented front-end pages using React and ReduxForm.
    • Implemented REST APIs using DjangoRESTFramework and optimized Django ORM queries.
    • Fixed mobile responsive issue on server side rendering in next.js using JavaScript packages such as Lodash.throttle.
    • Integrated Django-packages like tinyMCE editor and customize Django admin behavior.
    • Fixed cross-browser issues.
    Technologies: React, Redux-Form, Mapbox, Next.js, Django, DjangoRESTFramework
  • Full-stack Developer

    2018 - 2018
    • Worked on Aurum's hotel inventory management web application with Angular. As the only developer, I had managed the design, development, and deployment of the project.
    • Implemented a real-time messaging system and custom calendar feature and other business logic using Firebase.
    • Implemented a notification system using Firebase Cloud messaging.
    • Added cloud functions with Node.js as back-end API management for handling database.
    • Implemented business logic and built responsive front-end pages with Bootstrap.
    • Deployed the project using Firebase hosting service with custom user domain from GoDaddy.
    Technologies: Angular 5, React, FireBase
  • Full-stack Developer

    2014 - 2018
    • Contributed to multiple projects with React, Angular, Django, and AWS.
    • Built single-page applications with React (Redux-saga), AngularJS, and Angular.
    • Built React High-Order-Component to implement complement behavior and refactored JavaScript code.
    • Implemented optimized algorithms with the proper data structure to optimize rendering 3D models and its custom behavior in Node.js on a React project.
    • Implemented features and fixed issues in React-Redux-Form such as mobile-view rendering issue.
    • Worked on a Node + Redux-persist project with a lot of third-party APIs like Dropbox API and Google sheet API.
    • Worked on data visualization with HighCharts.
    • Wrote REST APIs with DjangoRESTFramework and Djagno server-side template with many other libraries like Djoser and Django-allauth.
    • Deployed and managed a live development and production server. For instance, deployed a Django application in Ubuntu 16.04 machine with Postgres and other tools and libraries like celery, ElasticSearch, and opensemanticsearch.
    • Wrote a deployment script with NodeJS and bash shell script.
    Technologies: React, Angular, Node.JS, Django, AWS, FireBase
  • Full-stack Developer

    2012 - 2014
    Altitude Labs
    • Built front-end pages with Bootstrap, JavaScript, HTML, and CSS.
    • integrated a lot of data from different data sources like "world bank" to a database using Python packages such as Numpy and Pandas Data Reader.
    • Worked on an image processing project with openCV and JavaCV like crowd detection.
    • Contributed to JSP projects with Apache tomcat.
    • Worked on WPF animation and desktop applications.
    Technologies: JavaScript, Python, Java, C#


  • React, GraphQL Project (Development)

    Developed a Quora-like site using React and React-Hook front-end with GraphQL and TypeScript for a home-care service company based in Australia.

  • Cloud-Based Workforce Management, HR, and Payroll Software (Development)

    Developed USA’s leading cloud-based workforce management, HR, and payroll software with Angular, Node.js, Express.js, GraphQL, Apollo, PostgreSQL, Bootstrap, etc.

  • Data Analysis and Visualization Project (Development)

    Developed project for the PowerforAll's data analysis project.
    Integrated a lot of often source code to the Django project and auto indexing documents with opensemanticsearch tool and visualize data with HighCharts and Mapbox.

  • React, Mapbox, Django Project (Development)

    Boston Hospital's medication provider search tool.
    Implemented front-end pages with React, ReduxForm and developed REST APIs using DjangoRESTFramework and integrated many Django packages like tinyMCE editor and customized Django admin behavior

  • React, Three.js Project (Development)

    Worked on a React.js project with Next.js framework.

    Built front-end pages with React, Redux-Persist, Saga and display Dicom images using Three.js.

    Code refactoring into ES7 and applying optimized algorithms to speed up rendering 3D models.

  • Hotel Inventory Management System (Development)

    Developed hotel inventory management web application at Aurum. I designed, developed, and deployed the project with Angular 5 and Firebase back end


  • Languages

    Python, JavaScript, Python 3, ECMAScript (ES6), TypeScript, GraphQL
  • Frameworks, Redux, Django, Angular, Express.js, Material-UI, Bootstrap 4, Vuetify.js, FeathersJS
  • Libraries/APIs

    Antd, React, Node.js, Vue.js, Highcharts, Vue.js 2, AmplifyJS, Redux-saga, Three.js, ApexCharts.js
  • Tools

    MongoDB Atlas, Mongoose, Celery, Redux Thunk, SendGrid
  • Platforms

    Firebase, AWS EC2, Twilio, Google Cloud Platform (GCP), Docker, AWS Lambda, Blockchain, Ethereum
  • Storage

    NoSQL, AWS RDS, PostgreSQL, Cloud Firestore, MongoDB, Elasticsearch
  • Other

    DjangoRESTFramework, TypeORM, Nest.js, Hooks, Firebase Cloud Functions, Front-end, Blockchain Developer, Apollo, Semantic UI, Microsoft Azure, Linux System Administration


  • Bachelor's degree in Computer Science
    2007 - 2011
    Chu Hai College of Higher Education - Hong Kong

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