Willian Fernandes, Ruby & JavaScript Developer in São José dos Campos - State of São Paulo, Brazil
Willian Fernandes

Ruby & JavaScript Developer in São José dos Campos - State of São Paulo, Brazil

Member since June 19, 2013
Willian is a Ruby/Ruby on Rails specialist who has been working in web development since 2002, with over seven years of Ruby experience. Besides Ruby, he likes to work with front-end technologies, like JavaScript, and is always learning what is new with this language. He is now helping Toptal by spreading the word about how good it is to be part of Toptal's network.
Willian is now available for hire



  • JavaScript, 16 years
  • CSS3, 16 years
  • Ruby, 10 years
  • Test-driven Development (TDD), 10 years
  • AngularJS, 4 years
  • React, 3 years
  • Redux, 3 years
  • ECMAScript (ES6), 3 years


São José dos Campos - State of São Paulo, Brazil



Preferred Environment

MacOS, VMWare Fusion, Docker, Vim, Headphones

The most amazing...

...thing I've built is a coaching subscription system for Habit.com using Ruby on Rails on the back-end and React on the front-end.


  • Senior Software Engineer

    2017 - 2018
    Habit.com (via Toptal)
    • Built the back-end for the client to run behind their kitchen using Ruby.
    • Restructured the private homepage using React and SCSS for styling.
    • Built the Results page entirely with React, React Router, and CSS-in-JS technique.
    • Redefined how the front-end codebase is structured and how new internal applications will be styled using a lib called Glamorous.
    • Participated in a small team to build their Coach Subscription program using Ruby on Rails and React.
    • Integrated an external service called TextIt to handle SMS communications between Habit, coaches, and customers that are participating in their coaching program.
    Technologies: Ruby on Rails, React, Docker
  • React.js Developer

    2017 - 2018
    Stabe (via Toptal)
    • Created a single-page application using React.
    • Created an authentication layer with API communication to avoid unlogged users accessing protected pages.
    • Built responsive pages for mobile and desktop devices.
    Technologies: React, Redux, React-router, Ramda
  • Web Develper

    2015 - 2016
    • Contributed to the company's public website and internal products.
    Technologies: Ruby, JavaScript, React, Redux
  • Web Engineering

    2014 - 2015
    • Helped the team to develop a new version of ArtList using Ruby on Rails and AngularJS.
    • Created an ID verification flow using IDChecker.
    • Worked with continuous deployment using Travis CI.
    • Worked with Stripe as the payment gateway.
    • Performed TDD/BDD with the RSpec and Jasmine framework.
    Technologies: Ruby on Rails, AngularJS, Heroku, ElasticSearch
  • Web Developer

    2013 - 2013
    • Developed the necessary software to take care of tasks on projects' ticket lists using Ruby on Rails, TDD, and client-side technologies including JavaScript, CoffeeScript, CSS3, and HTML5.
    • Worked as part of the SwagExpert project team.
    • Used CoffeeScript and SLIM template for the first time.
    • Performed TDD/BDD with the MiniTest framework.
    • Used the Heroku environment and CI policy.
    Technologies: Ruby, JavaScript, CoffeeScript, CSS, Sass
  • Web Engineer

    2012 - 2013
    • Helped a team developing a new eCommerce platform using Ruby, Ruby on Rails, JavaScript, HTML5, CSS3, MySQL, and MongoDB on the AWS platform.
    • Used all features of the AWS platform.
    • Worked on a hybrid project with MySQL and MongoDB.
    • Worked with continuous deployment.
    • Tested JavaScript with Jasmine.
    Technologies: Ruby, Rails, AWS SDK, JavaScript, CSS, HTML5
  • Web Developer

    2012 - 2012
    • Worked on SellSimple.com as a freelance web developer helping to solve several production problems.
    • Joined the team when SellSimple.com was already in production. Tackled a variety of open tickets on GitHub issues.
    • Worked with a RESTful API written with Rails.
    • Worked on a non-DB Rails project. Used the API to store and read data and also to authenticate users.
    • Worked with an international company for the first time.
    Technologies: Ruby, Ruby on Rails
  • Developer Team Leader

    2011 - 2012
    • Worked on a new e-learning platform using best practices in Ruby on Rails, MySQL, and Node.js. Proved that the company can grow with a small and focused team.
    • Used Node.js to build a chat interface allowing students to talk with each other and their instructors.
    • Created an entire production environment on Linode.com (SysOp).
    • Converted the existing .NET application into a Ruby on Rails application.
    • Led the development team.
    Technologies: Ruby, Ruby on Rails, Node.js, HTML, JavaScript, CSS, HTML
  • Web Developer

    2010 - 2011
    • Worked with Ruby on Rails in the development of a new vocational guidance platform to help young people find the best career.
    • Created an Agile Scrum culture in the company.
    • Introduced a TDD culture to the development team and taught other developers how to test code.
    • Built several Dojos with the team.
    • Led the development team as CTO.
    Technologies: Ruby, Ruby on Rails, JavaScript, HTML, CSS
  • Web Developer

    2009 - 2010
    • Worked as a freelancer on many projects including the website for Billboard, a Brazilian company.
    • Worked with PHP, Python, and Ruby depending on project requirements.
    Technologies: Ruby, Ruby on Rails, HTML, CSS, JavaScript


  • Swag Expert (Development)

    An eCommerce site focused on the swag industry.

  • Baby.com.br (Development)

    A new way to think about eCommerce in Brazil. The website focuses on moms and babies and provides a fast, elegant, deliverable, and smart eCommerce solution.

  • eDivv (Development)

    "eDivv will help you discover new possibilities in your beauty world. Sign up today and start trading unwanted beauty sample products for those coveted items you would love to try!"

  • ArtList (Development)

    ArtList is an online marketplace where collectors can buy and sell fine art confidentially. We take a flat 10% commission on artworks sold and share it 50–50 with artists. Our mission is to make the global art market fast, secure and fair. We’re based in New York City.

  • GRID Invitational (NPGL) (Development)

    Using AngularJS on the client-side and Ruby on Rails on the server-side, I helped NPGL to build GRID Invitational application.

  • Habit.com (Development)

    Habit offers science-based nutrition plan based on customer's DNA.

  • MailCharts (Development)

    MailCharts saves you the trouble of secretly subscribing to your competition’s emails and spending hours trying to find something actionable.

  • StickerMule (Development)

    Sticker Mule is the fastest and easiest way to buy custom stickers.


  • Languages

    ECMAScript (ES6), HTML5, JavaScript, CSS3, SCSS, Ruby, GraphQL, Python
  • Frameworks

    Ruby on Rails (RoR), Redux, AngularJS, minitest, Jasmine, Ember.js, Django
  • Tools

    Vagrant, GitHub, RSpec, Ansible, Git, Adobe Photoshop, Adobe Illustrator, Adobe Fireworks
  • Paradigms

    Extreme Programming, Test-driven Development (TDD), Behavior-driven Development (BDD), Pair Programming, Scrum, Kanban, Agile Software Development, UX Design
  • Platforms

    MacOS, Linux, Amazon Web Services (AWS), WordPress
  • Storage

    JSON, Memcached, Redis, AWS S3, PostgreSQL, MongoDB, MySQL, SQLite, Amazon SDB, AWS DynamoDB, AWS RDS
  • Other

    RESTful Web Services, Front-end Development, User Experience (UX)
  • Libraries/APIs

    React, jQuery Mobile, Facebook API, Node.js


  • Master's degree in Computer Engineering
    2004 - 2007
    IBTA - Sao Paulo

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