Sergio Antonio Milici, Progressive Web Applications (PWA) Developer in Buenos Aires, Argentina
Sergio Antonio Milici

Progressive Web Applications (PWA) Developer in Buenos Aires, Argentina

Member since May 20, 2014
Sergio is a software engineer with a talent for developing scalable and efficient solutions for complex problems. He has a comprehensive understanding of design processes with experience in all the design stages of a product, including research, development, scalability, and testing.
Sergio is now available for hire




Buenos Aires, Argentina



Preferred Environment

Web, iOS, Android, Ionic, Angular, React, Node.js, CSS, JavaScript

The most amazing...

...project I've created is a distributed system to control all software and hardware changes on every machine in a network.


  • Senior Front-end Software Engineer

    2019 - 2020
    TalentWall (Toptal Client)
    • Created a drag-and-drop grid system to build custom dashboards from a set of resizable charts allowing the user to modify the position on the dashboard.
    • Improved user navigation experience by 40% fixing algorithms to process +5,000 jobs.
    • Designed multiple UI filters to be used across apps.
    Technologies: Sass, TypeScript, Angular, CSS, JavaScript
  • Senior Full-stack Software Engineer

    2019 - 2019
    Social Camping
    • Set up the back end with Node.js, Express, and Firestore to manage the user's assets.
    • Integrated Firebase Auth to allow users to login with Google, Facebook, and with email and password.
    • Created the front-end project with Angular and Bootstrap for implementing a CRUD to allow users to manage their camping assets.
    • Implemented Figma design to create reusable UI system components.
    Technologies: Bootstrap, Firebase, Angular, Express.js, Node.js, CSS, JavaScript
  • Senior Software Enginner

    2016 - 2018
    Qwil (Toptal Client)
    • Built the first release product of Qwil's web application in AngularJS.
    • Migrated and rebuilt the web application in the React ecosystem.
    • Created the UI components to build out Qwil's design system with the lead product designer.
    • Reduced 90% of web app load time, implementing lazy load components.
    • Set up and implemented a standardized E2E testing platform with Docker and Nightwatch for multiple environments to ensure software release quality.
    • Implemented unit testing to improve the development process that was adopted company-wide, which resulted in reducing bugs by 50%.
    Technologies: Enzyme, Jest, Sass, Babel, Webpack, Flow, Redux, React, CSS, JavaScript
  • Mobile Engineer

    2015 - 2015
    Hollaback! (Toptal Client)
    • Created a hybrid HTML5 mobile app from scratch for Android and iOS using Ionic.
    • Designed and implemented business logic in JavaScript following design patterns and best practices.
    • Deployed builds to production for Android and iOS using TestFlight and Google Play.
    • Integrated native plugins like geolocation, contacts, and keyboard.
    • Integrated Facebook native login and Google Maps API.
    Technologies: JavaScript, Sass, Ionic, AngularJS, CSS
  • Front-end Software Engineer

    2015 - 2015
    Kimono (via Topta)
    • Redesigned chat workflow for sending and receiving messages.
    • Created the mobile version using Ionic Framework.
    • Refactored and designed the OOP model.
    • Implemented Algolia search API.
    • Improved performance on mobile versions.
    Technologies: JavaScript, CSS3, HTML5, iOS, Android, Cordova, Ionic, AngularJS
  • Java DevOps Consulting

    2014 - 2014
    L2 (via Toptal)
    • Converted five Java projects to Maven projects.
    • Designed and implemented a configuration module to support multiple environments using Typesafe/Conf.
    • Set up automatic builds on Jenkins with GitHub.
    Technologies: Jenkins, Maven, Java
  • Software Engineer

    2012 - 2014
    • Created back-end server for an ad targeting system for Facebook Games.
    • Developed a JavaScript library to serve ads based on game states.
    • Designed a real-time metric system on HTML5 for showing user conversions.
    • Created a Java back-end server for a Space Pirates game. Integrated it with Android and Facebook.
    • Managed AWS to support all systems, including handling databases, fail-over, and performance.
    Technologies: Redis, MySQL, JavaScript, Spring, Jasmine, PHPUnit, JUnit, PHP, Python, Java
  • Software Engineering Tech Lead

    2009 - 2012
    • Created a multi-platform client-server application to control hardware and software changes over the whole network.
    • Developed a multi-platform client application on C++.
    • Implemented high concurrency to handle all changes on thousands of computers.
    • Managed the team and development.
    • Made the back-end to scale and processed huge amounts of data.
    Technologies: Java, PHPUnit, Jenkins, Memcached, MySQL, HTML5, PHP, C++
  • C++ Developer

    2006 - 2009
    • Designed a stock system to control all company assets.
    • Created a MFC UI.
    • Analyzed and designed MySQL schema.
    • Created an installer and deployment tool for control updates.
    • Designed the migration to web.
    Technologies: Web, Microsoft Foundation Class Library (MFC), MySQL, C++


  • InvGate Assets

    Assets is a suite of intelligent solutions to manage change and maximize the use of resources and make informed IT decisions.
    I designed it from the very start, including creating and deploying software and handling metering, inventory, and change management modules.

  • Space Pirates

    Space Pirates is a mobile game for Android and iOS built with Unity3D. I designed the back-end server to handle thousands of concurrent users, using Netty and Spring.

  • BEE

    BEE is an online ad server designed specifically for 50Cubes' games. It was custom built to allow us to flexibly optimize the ads being served in our various games.
    It was made on PHP, MySQL, Redis, HTML5, JavaScript, and Python.

  • Hollaback!


  • Toptal Mentor
    Sergio is a mentor in the Toptal Global Mentor’s Program. This program is a partnership between Toptal and General Assembly to provide high quality mentorship for students from minority and low income backgrounds who are looking to begin their careers as professional software engineers. Sergio shows commitment to diversity in tech by mentoring a General Assembly student every week for a year, covering everything from coding tips and tricks to advice on making it in the industry.


  • Languages

    HTML, CSS, ES7, Sass, ECMAScript (ES6), JavaScript, Java, TypeScript 3, TypeScript, HTML5, PHP, Xtend, SQL, C++, GraphQL, Python, CSS3, C
  • Frameworks

    Angular, Redux, Jasmine, Ionic, AngularJS, Ionic 4, Selenium, Bootstrap, Express.js, Jest, Next.js, PHPUnit, JUnit, Spring
  • Libraries/APIs

    React, RxJS, NgRx, Google Maps, Facebook API, REST APIs, AngularUI, Node.js, RequireJS, Microsoft Foundation Class Library (MFC), Socket.IO, Twitter API, YouTube API, jQuery, NgRx/store
  • Tools

    Bower, Maven, Webpack 4, SAP Hybris, Webpack, Babel, Grunt, Karma, NPM, Mocha, Gulp, Git, Flow, Jenkins, Amazon CloudFront CDN, Google Analytics, Subversion (SVN)
  • Paradigms

    Test-driven Development (TDD), Object-oriented Design (OOD), Functional Reactive Programming, Model View Viewmodel (MVVM), Model View Controller (MVC), Web Performance Optimization (WPO), Reactive Programming
  • Storage

    NoSQL, MongoDB, Redis, MySQL, Memcached, Microsoft SQL Server
  • Other

    Freelance, Single-page Applications (SPA), Cordova, Hybrid Apps, Front-end Development, Progressive Web Applications (PWA), Front-end, Capacitor, SaaS, System Administration, Open Source, Architecture, Apps, Web Components, Enzyme
  • Platforms

    MacOS, Firebase, Windows, Linux, Web, Android, iOS, Parse


  • Master of Engineering Degree in Information Systems Engineering
    2005 - 2012
    National Technological University - Buenos Aires, Argentina

To view more profiles

Join Toptal
Share it with others