Joseph Halter, Software Developer in Hobscheid, Luxembourg
Joseph Halter

Software Developer in Hobscheid, Luxembourg

Member since February 10, 2015
Joseph is a full-stack developer with 10+ years of experience. He loves using Elixir or Ruby on Rails on the back end. He enjoys using React or Ember on the front end. After having worked in the finance industry for years, he's constantly in search of new challenges.
Joseph is now available for hire




Hobscheid, Luxembourg



Preferred Environment

Visual Studio Code, Git

The most amazing...

...thing I've built is an HRIS solution used daily by thousands of employees across the world.


  • Partner

    2016 - PRESENT
    Openhood sarl
    • Consulted for various small to medium businesses.
    • Scaled a transactional REST API to multiple servers using RabbitMQ for messaging between the servers.
    • Created a static website generator tailored to the specific needs of a customer.
    • Used Ember.js and Semantic UI to create a single-page web application for both mobile and desktop users.
    • Created a marketplace with exchanges in multiple currencies and real-time chat between the users.
    • Created a multiplayer 3D web game using Babylon.js and Elixir/Phoenix with GraphQL for the back end.
    • Created a single-page application React website with animated components, front-end side tests, and a library of components using Storybook with responsive design for mobile/tablet/desktop. Used GraphQL with Elixir/Phoenix in the back end.
    • Handled GDPR compliance for a very large Rails application including integration with 10+ external providers, each with their own API integration, including Stripe, Onfido, Braze, AppsFlyer, Mailchimp, ZenDesk, and more.
    • Organized a web-based contest where people can win a $100,000 free roll then later a $250,000 free roll with timer, real-time charts and visualizations, email notifications, a full web admin interface with filtering and reporting with exports in multiple formats.
    • Allowed people to sign up using Twitter, Facebook, or email, track the signed-in user's Twitter friends, and allowed the user to share multiple events with their followers, optimize display of posts on Twitter as a nice card, and optimize for a perfect Google page speed score.
    Technologies: RabbitMQ, PostgreSQL, Ember.js, Elixir
  • Senior Developer

    2011 - 2016
    Talentbox SA/Metrilio SA
    • Migrated a dozen separate customer-specific Rails applications into a new unified configurable online platform, reducing the time to set up a new customer from one month to three days.
    • Maintained a very large Rails codebase with hundreds of tables and models, undergoing several re-factoring processes to always allow for adding new features while keeping maintenance time under control.
    • Added thousands of integration tests to avoid regressions, reduce errors, and reduce the need for human testing, which was previously a full-time job for one person.
    • Improved production from one deployment per month to multiple deployments per day.
    Technologies: PostgreSQL, Ruby on Rails (RoR), JavaScript, CSS, HTML
  • Software Architect

    2009 - 2011
    Kneip Communication SA
    • Created a platform for financial institutions to browse their fund publication matrix, allowing them to view and search in real time inside the content of a report that the company couldn't generate daily anymore due to a stressed Oracle database with a lot of stored procedures.
    • Built a multiple-internal API to synchronize legacy applications developed in different programming languages together.
    • Programmed a mail robot API to communicate with ClearStream during all the steps of the fund creation in order to get a new ISIN code.
    • Developed a new platform to centralize all the documents related to funds and allow fast batch import of data in a bi-temporal database with a very complex permission system.
    Technologies: MongoDB, PostgreSQL, Ruby on Rails (RoR), JavaScript, CSS, HTML
  • Computer Programmer

    2006 - 2009
    Akira Web SA
    • Created a website in 17 languages for Chanel promoting their latest perfume.
    • Built a communication platform for the leadership of a leading international steel and mining company via SMS notifications.
    • Programmed an in-house CMS in PHP to power websites localized in many languages, allowing people to create their own forms and wizards and bind them to multiple custom services.
    • Handled multiple dedicated servers and scaled PostgreSQL to multiple servers.
    • Started using Rails more and more often to develop prototypes even faster.
    Technologies: Ruby on Rails (RoR), PostgreSQL, Flash, MySQL, PHP, JavaScript, CSS, HTML
  • Developer

    2006 - 2006
    Artic Media Sàrl
    • Created a platform to find real estate based on geolocation grouped by labor pool.
    • Built a website for a jewelry store with great attention to usability and accessibility.
    • Programmed a website for a big local shopping center from scratch and worked on SEO until it was in the top 10 on Google searches for all relevant keywords, and even ranked 1st when searching on just the name of the city for multiple months.
    • Organized online contests where it's possible to win real money, and worked on preventing people from being able to cheat the system.
    Technologies: Flash, MySQL, PHP, JavaScript, CSS, HTML
  • Analyst/Programmer

    2005 - 2006
    Lorweb Sàrl
    • Converted manual entries for a local football team into a searchable database with intelligible charts.
    • Extended an in-house CMS to allow customers to create new pages in multiple languages more easily.
    • Created a task to load, parse, and sync multiple directories of XML files with an online database.
    • Scaled a Microsoft SQL-based website by creating specific indexes and optimizing query speed for paginated objects.
    Technologies: Microsoft SQL Server, ASP.NET, JavaScript, CSS, HTML
  • CEO

    2001 - 2005
    Ekzakt Sàrl
    • Managed customer expectations; responsible for estimates and team planning.
    • Launched a successful multilingual online store to sell art pieces.
    • Converted 2D schematics into 3D graphics, improved customer/dealership communication, and learned how to register a patent.
    • Helped a customer digitize his growing paper documents archive.
    • Taught clients webmaster skills necessary to keep their company websites up-to-date.
    • Used Flash vector and scripting capabilities to create responsive websites, serving different content depending on resolution.
    Technologies: Blender, Flash, MySQL, PHP, JavaScript, CSS, HTML



  • Languages

    SCSS, Elixir, JavaScript, Ruby, CoffeeScript, CSS, HTML, TypeScript, GraphQL, CSS2, CSS3, SQL, HTML5, HTML4, ECMAScript (ES6), JavaScript 5, JavaScript 6, TypeScript 2, TypeScript 3, PHP
  • Frameworks

    Phoenix, Ember.js, Sinatra, Ruby on Rails (RoR), Jest, Redux, Ruby on Rails 3, Ruby on Rails 4, Ruby on Rails 5, Bootstrap, Business Rules Engine, Bootstrap 3, Bootstrap 2, Bootstrap 3+, ASP.NET, Unity3D, RubyMotion, Express.js
  • Libraries/APIs

    REST APIs, Ember Data, jQuery, PayPal API, Sequel, React, Ruby on Rails API, React Redux, JSON API, SendGrid API, Immutable.js, Babylon.js, Node.js, Three.js, Vue
  • Tools

    React Apollo, GitHub, Cucumber, RSpec, Git, GitLab, JSS, SendGrid, Vim Text Editor, AWS SDK, JavaScript Debugging, Flash, Blender, RabbitMQ, Webpack, Webpack 4, Webpack 3, Webpack 2
  • Paradigms

    Testing, Test-driven Development (TDD), Behavior-driven Development (BDD), Functional Programming, Refactoring, Pair Programming, REST, Object-oriented Programming (OOP), Agile Software Development, Continuous Integration (CI), Requirements Analysis, Continuous Deployment, Web Architecture
  • Platforms

    Godot, Heroku, Mailgun, Amazon Web Services (AWS), Visual Studio Code
  • Storage

    PostgreSQL, PostgreSQL 10.1, JSON, MySQL, Amazon S3 (AWS S3), Memcached, Redis, Microsoft SQL Server, MongoDB
  • Other

    Single-page Applications (SPA), Responsive UI, API Integration, Ember CLI, Prototyping, Regular Expressions, Application Security, APIs, Workflow Modeling, Software Architecture, Bitemporality, Pub/Sub, Web Components, Scalability, User Experience (UX), Debugging, Architecture, Visualization, Ruby Gems, Ruby Performance, JavaScript Libraries, CSS Grid, CSS3 Animation, User Interface (UI), eCommerce, Technical Leadership, Apollo, App UI, App UX


  • DEUG (Equivalent to Bachelor's) Degree in Computer Science
    1998 - 2000
    Université de Metz - France

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