Jonatan Fekete, Full-stack Developer in Barcelona, Spain
Jonatan Fekete

Full-stack Developer in Barcelona, Spain

Member since January 2, 2017
Johnny is a full-stack developer who specializes in building customer-facing web applications and business systems. He has more than a decade of experience in architecture design, PHP development, database engineering, and web-based front-end technologies. Johnny joined Toptal to find fresh companies with a growth mindset where original ideas are acknowledged and where he could contribute to the final product.
Jonatan is now available for hire


  • TokenMetrics
    MySQL, AdonisJS, D3.js, ECMAScript (ES6), Redux, React, Node.js
  • TicketSub
    Git, Continuous Integration (CI), DigitalOcean, Docker, Jest, Redis, Redux...
  • Recruitio
    Amazon Web Services (AWS), AWS, Git, Sass, React, jQuery, JavaScript...



Barcelona, Spain



Preferred Environment

React, Laravel, Webpack, NPM, Composer, Sublime Text, MacOS

The most amazing...

...project I've worked on was an applicant-tracking system that I designed and built from scratch and led it to success.


  • Full-stack JavaScript Developer

    2018 - 2019
    • Created a React-based web app from scratch and followed the provided designs.
    • Designed the database, system architecture, models, and relations.
    • Built the data-heavy back end in Node.js with AdonisJs, following the framework's best practices (about architecture, events, authentication).
    • Connected to multiple APIs to retrieve massive amounts of financial and statistical data.
    • Created complex data visualizations with D3.js.
    Technologies: MySQL, AdonisJS, D3.js, ECMAScript (ES6), Redux, React, Node.js
  • Full-stack Developer

    2018 - 2018
    • Created from scratch a React-based web app that followed the provided designs.
    • Designed the database, system architecture, models and relations.
    • Built the back end in Laravel, following the framework's best practices (about architecture, events, notifications).
    • Connected to multiple APIs (Google APIs, Stripe payment integration, Twilio, and SendGrid).
    • Set up Elasticsearch and Redis and optimized the system's performance.
    • Configured continuous integration, deployment, and scalable development processes.
    Technologies: Git, Continuous Integration (CI), DigitalOcean, Docker, Jest, Redis, Redux, Elasticsearch, MySQL, Laravel, ECMAScript (ES6), React
  • Full-stack Developer | Co-founder

    2016 - 2018
    • Created an online applicant tracking system from scratch.
    • Converted the business concepts and processes into architectural plans and developed a user-friendly online application.
    • Used Laravel as a back-end framework with multiple integrations including Elasticsearch, a Word-to-PDF conversion, and third-party APIs.
    • Developed a responsive, highly interactive front end.
    • Configured the underlying server architecture, managed the development, and implemented continuous integration environment.
    • Wrote unit and end-to-end tests, scaled the system, and constantly improved the stability of the product.
    • Managed the underlying server architecture (AWS and later Digital Ocean).
    Technologies: Amazon Web Services (AWS), AWS, Git, Sass, React, jQuery, JavaScript, Elasticsearch, Laravel, PHP
  • Full-stack Developer

    2016 - 2017
    Starfly Media ApS
    • Developed the server-side web application logic and integrated an internally used system.
    • Connected a Symfony application to numerous APIs and automated the processing of massive amounts of data.
    • Implemented various optimization caching techniques to enable a high performance.
    • Added visual interfaces to provide an overview of the running processes and created statistic dashboards to give real-time insights.
    Technologies: jQuery, JavaScript, HTML5, Symfony, PHP
  • Back-end Developer

    2016 - 2016
    Elements Interactive
    • Collaborated with cross-functional teams to design and implement new features and services to support our client applications.
    • Created a back-end and REST API for a mobile platform.
    • Modernized an existing PHP application and implemented Elasticsearch.
    • Introduced new functionalities that were supported by unit tests using PHPUnit and Composer.
    Technologies: Git, jQuery, JavaScript, HTML5, Elasticsearch, MySQL, Django, Python, Laravel, PHP
  • Full-stack Developer

    2015 - 2016
    • Worked on multiple marketing-driven projects with a very short turnaround in a fast-paced digital agency.
    • Created numerous online games and websites.
    • Customized WordPress to satisfy client needs; optimized them to stay fast and functional even with high traffic.
    • Integrated various third-party APIs for data visualization and social media statistics.
    Technologies: Git, MySQL, jQuery, JavaScript, HTML5, WordPress, PHP
  • Full-stack Developer

    2012 - 2015
    • Designed and developed the front end of a business process management system.
    • Worked extensively on the front end doing everything from designing the user interfaces to creating the HTML and CSS and adding a rich user interaction.
    • Integrated different APIs and libraries while making sure that the client-server communication is seamless.
    • Wrote PHP scripts to facilitate the development of the application.
    • Managed the AWS setup of the system.
    Technologies: Amazon Web Services (AWS), AWS, Backbone.js, jQuery, JavaScript, CSS, HTML5, MySQL, PHP
  • Web Application Engineer

    2011 - 2012
    InvenQ Insight
    • Worked on a cloud-based business process modeling system.
    • Designed and developed the platform from scratch, using various server- and client-side technologies.
    • Implemented custom HTML canvas functionalities for working with flow models.
    Technologies: Git, CSS, HTML5, jQuery, JavaScript, MySQL, PHP
  • Lead Web Developer

    2011 - 2012
    Pegasus Online Media
    • Planned, designed, and developed a vertical price comparison site.
    • Consolidated numerous webshops' product catalogs through APIs.
    • Integrated a social network functionality to the existing sites, maximized the search engine optimization, and worked with data security.
    Technologies: CSS3, HTML5, jQuery, JavaScript, MySQL, PHP
  • Software Developer

    2007 - 2011
    Jonatan Fekete e-Solutions
    • Created numerous websites and web shops.
    • Customized WordPress and its plugins to achieve specific client requirements.
    Technologies: Amazon Web Services (AWS), AWS, jQuery, JavaScript, CSS, HTML5, MySQL, PHP


  • React Native Application for Retail Employees

    As a CTO and lead developer, I worked in a Barcelona-based startup, Beam HR. Our application is used by the employees of various retails stores in Spain to view their schedules, request holidays and changes, notify their managers of sick leaves or chat with coworkers.

    The application communicates with different back-end APIs and uses technologies such as notifications, GPS, or local database.

    As a developer, I worked on both the back- and front-end side of the project, while simultaneously focusing on optimization, easy-to-use UI interfaces, error-proof infrastructure, and writing clean code.

  • Recruitio

    Recruitio is a digital talent sourcing tool that improves the process of finding the best candidates for your job openings.

    As a technical co-founder, I built the whole system from scratch, made all initial technological and architectural decisions, chose the back-end and front-end technologies, and implemented the system through an agile development process. The system was integrated with various external services, and I implemented an assortment of features such as Elasticsearch or Word-to-PDF conversion.

    After our user base started increasing, I ensured that the system could scale and function smoothly while always protecting sensitive client data. I introduced continuous integration, efficient development, and deployment processes.

  • Back End for a Location-tracking Mobile App

    I worked with a team at Elements Interactive to build a location-tracking application to prevent young people from using their phones while riding.

    I developed the admin interface and the REST API that served hundreds of users simultaneously at peak periods. I also implemented the testing and access management with multi-level user roles.

  • Weekly Meal Planner

    As part of Isobar, I worked on a project for one of Denmark's largest grocery stores. The web app consisted of hundreds of meal recipes and let users mix and match them to plan ahead for their week, generating a consolidated shopping list at the end.

    Although the project was part of a WordPress environment, I developed many custom functionalities in PHP and JavaScript.

  • Mentoring Others in Code

    I believe that it's never too late to learn to code, and in the previous years, I organized many free web and PHP introduction courses—helping more than a hundred people in total.

    Besides that, I mentored several beginners and helped them get their first developer jobs. I also organized some small hackathons to motivate them and show how much can be achieved within just a weekend.

  • Pruexx | An Online Business Process Modeling System

    I created a web app at the dawn of HTML5 Canvas so I had to write custom functionalities in order for users to be able to drag and drop elements, connect them, edit properties, and format.

    I used JavaScript, jQuery, and many libraries to achieve smooth user experiences while the back-end ran on PHP with MySQL.


  • Languages

    CSS, CSS3, JavaScript, PHP 7, JavaScript 6, PHP, SQL, Sass, HTML5, Python, ECMAScript (ES6), Objective-C, Swift, Python 3, GraphQL
  • Frameworks

    Laravel, React Native, Laravel 5, Symfony 3, Symfony, Redux, OAuth 2, PHPUnit, AdonisJS, Django, Jest
  • Libraries/APIs

    jQuery, jQuery UI, React, Node.js, Facebook API, FPDF, Google Maps, D3.js, REST APIs, Backbone.js
  • Tools

    GitHub, Sublime Text 3, Git, Trello, Xcode, wkhtmltopdf, Sketch, Photoshop CC, Illustrator CC, Nginx, Composer, Sublime Text, Interface Builder, Webpack, NPM, Jira
  • Paradigms

    REST, Scrum, Agile, Kanban, E2E Testing, Continuous Integration (CI)
  • Platforms

    WordPress, Visual Studio Code, Firebase, iOS, Linux, Ubuntu, AWS EC2, Unix, Apache2, MacOS, DigitalOcean, Amazon Web Services (AWS), Docker
  • Other

    GitFlow, Ajax, Axios, OOP Designs, App UX, WordPress Plugins, WordPress Themes, AWS, SaaS, Web App Development, Back-end, Front-end
  • Storage

    Elasticsearch, MySQL, AWS S3, MongoDB, NoSQL, Redis


  • Master's degree in Business Administration and Information Systems
    2012 - 2016
    Copenhagen Business School - Copenhagen, Denmark
  • Bachelor's degree in Business Information Systems
    2007 - 2011
    Corvinus University of Budapest - Budapest, Hungary

To view more profiles

Join Toptal
Share it with others