Alan Kralj, Developer in Zagreb, Croatia
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Alan Kralj

Verified Expert  in Engineering

Software Developer

Zagreb, Croatia
Toptal Member Since
June 7, 2016

Alan is a full-stack web developer and an experienced programmer with a diverse skillset built over 15 years of professional work. Along with having architected and developed numerous web applications and award-winning websites, he loves both the challenge of solving complex problems and satisfaction of building well-crafted and maintainable software.


Bad Cog
Unity3D, C#, 3D Graphics, Procedural Generation, User Interface (UI)...
Performitiv (via Toptal)
Sass, Vue, MongoDB, Webpack, AngularJS, Vuex, Vue 2, Node.js, CSS3, HTML5...
Bad Cog
Sass, Unity3D, C#, Linux, Node.js, CakePHP, PHP, AngularJS, Vue, JavaScript...




Preferred Environment

Shell, Git, Visual Studio Code (VS Code), Linux

The most amazing... I've done recently was programming the procedural 3D graphics for a computer game, representing complex terrain created from simple, randomly seeded rules.

Work Experience

Programmer | Co-founder

2019 - PRESENT
Bad Cog
  • Developed a PC strategy game for a small indie game dev studio, currently building toward an EA launch.
  • Programmed procedural 3D graphics and effects (most of the game graphics are procedural). Worked on rendering pipeline, post-processing, and general graphics development.
  • Developed general systems like input or camera handling and worked on various parts of game logic.
  • Built the entire game UI with the Unity UI Toolkit, which uses a familiar web stack.
Technologies: Unity3D, C#, 3D Graphics, Procedural Generation, User Interface (UI), User Experience (UX), UI Toolkits, Unity, FMOD, JSON, GitHub

Senior Front-end Developer

2017 - PRESENT
Performitiv (via Toptal)
  • Worked on upgrading the technology stack and UI/UX for the company's SaaS application. Efforts stretched over several longer development cycles, during which most of the application was migrated from AngularJS to the modern Vue stack.
  • Built a modern app UI using HTML5, CSS3, Sass, and several UI toolkits.
  • Developed complex custom components for both AngularJS and Vue parts of the application.
  • Built several custom charting components, some based on Google Charts and Chart.js, others using SVG directly.
  • Architected and developed the front end for another companion Vue application.
Technologies: Sass, Vue, MongoDB, Webpack, AngularJS, Vuex, Vue 2, Node.js, CSS3, HTML5, Front-end, NPM, JavaScript, Web Applications, User Interface (UI), User Experience (UX), HTML, APIs, JSON, GitHub, Amazon S3 (AWS S3), Databases, Bootstrap

Freelance Developer | Owner

2015 - 2022
Bad Cog
  • Worked as an architect and front-end engineer developing a platform for building GIS-oriented web applications.
  • Developed a web application for managing player assets, deck building, and card trading in an upcoming digital card game.
  • Acted as a core developer on a collaborative web whiteboard application.
  • Worked as a front-end engineer on a web application for data-driven measurement and improving business performance using AngularJS and Node.js.
  • Developed the front ends for two award-winning web presentations with advanced effects and interactions.
  • Consulted on integrating 3rd-party interactive systems into a client's application.
Technologies: Sass, Unity3D, C#, Linux, Node.js, CakePHP, PHP, AngularJS, Vue, JavaScript, jQuery, CSS3, HTML5, Front-end, NPM, Canvas, Web Applications, User Interface (UI), User Experience (UX), 3D Graphics, Procedural Generation, HTML, TypeScript, Angular, Unity, Game Development, Multiplayer, GIS, APIs, JSON, GitHub, Amazon S3 (AWS S3), MySQL, Nuxt.js, Tailwind CSS

Front-end Developer

2014 - 2015
  • Developed front-end interfaces and interactions on several media-rich websites.
  • Built an HTML5 and JavaScript web metronome app as a replacement for an old Flash version. The new app used native web technologies and modern APIs like WebAudio, and it had a scalable SVG interface.
  • Constructed prototypes of in-house projects, such as a visual mind-mapping tool.
Technologies: CSS, Sass, PHP, HTML, JavaScript, jQuery, CSS3, HTML5, Front-end, NPM, User Interface (UI), User Experience (UX), JSON, GitHub, Bootstrap

Senior Web Developer

2013 - 2014
Good Code
  • Built a CRM and billing system as an MVC web interface on top of a REST API.
  • Developed a rich interface for a web application that analyzes and visualizes the performances of athletes over time through video recordings embedded with statistical metadata.
  • Created several data visualization components built on top of D3.js.
  • Created several Angular prototype applications for in-house projects.
Technologies: CSS, Sass, D3.js, Angular, Django, Python, HTML, JavaScript, jQuery, CSS3, HTML5, Front-end, Canvas, Web Applications, APIs, JSON, GitHub, Databases, Bootstrap

Lead Developer | Co-founder

2009 - 2013
north2 | creative digital studio
  • Prepared the technology stack, best practices, and production process for a small development team.
  • Built several award-winning visual web presentations for various companies or projects. The hallmark of each was a highly creative design and advanced effects and interactions.
  • Developed an editorial web application for a small publishing company—covering the entire publishing process with automated creation and dispatching of electronic publications to subscribers.
  • Maintained an in-house framework for rapid development of web applications; most of the framework was open-sourced.
Technologies: Linux, PostgreSQL, JavaScript, CakePHP, PHP, jQuery, Front-end, Web Applications, User Interface (UI), User Experience (UX), HTML, APIs, JSON, Databases, MySQL

Senior Web Developer

2008 - 2010
  • Built and maintained a framework for rapid development of web applications; used on several company projects.
  • Developed several complex business web applications for government and public services, and managed parts of the development process.
  • Built a GIS visual mapping application on top of OpenLayers.
  • Gave in-house lectures and talks on various development topics and internal frameworks to a development team of 15.
Technologies: Spring MVC, Groovy, Java, JavaScript, Front-end, Web Applications, HTML, GIS, APIs, JSON

Web Developer

2004 - 2008
  • Engineered a booking and payment system for a medium-sized online travel agency.
  • Developed several applications for various product web catalogs.
  • Built a content management system used for both public and in-house websites and services; using mainly XML data and XSLT to create APIs and interfaces.
Technologies: CSS, XML/XSLT, Spring MVC, Java, HTML, JavaScript, Front-end, Web Applications, APIs

Performitiv Analytics App
A commercial web platform for learning analytics.

I'm the lead front-end developer on the project, building custom components and visualizations for new product features. Besides that, I've worked on upgrading the technology stack and UI/UX, migrating the application from AngularJS to a modern Vue stack.

Web Metronome | App
I built a web metronome app as a tech upgrade to an old Flash version. While the look and functions stayed the same, the new app uses native web technologies and only modern APIs like Web Audio and a scalable SVG interface.

Deckbound Heroes | Game and Collection Manager App

I contributed to the development of a web application for Deckbound Heroes: an upcoming digital card game. The app is used to manage player profiles and assets as well as for deck builds and card trades between players. It's built on top of Node.js and parts of the application are also embedded inside the game client.

My work on the project involved rewriting the old back-end app, setting up best practices and tools, and building the new UI and various API endpoints. I most enjoyed working on the interactive deck builder, which is also used inside the game client app.

A Web Whiteboard | App

AWW is a touch-friendly online whiteboard app used for collaborative drawing. Compatibility with a wide array of devices and screen sizes, easy sharing, and an embeddable widget for third-party applications are some of its more exciting features.

I contributed to the project as a core developer for over 1.5 years.


Lodash, Vue, jQuery, Vue 2, HTML5 Canvas, AngularUI, Snap.svg, Velocity.js, Google Chart API, Vuex, OpenLayers, RxJS, Node.js, D3.js, FMOD


Git, Gulp, NPM, Canvas, GitHub, GIS, Shell, Babel, Webpack, Composer, Bower, Grunt, Make, MongoDB Atlas


Unity3D, Unity, Angular, Bootstrap 3+, CakePHP, AngularJS, Bootstrap, Spring MVC, Laravel, Django, Vuetify, Nuxt.js, Tailwind CSS


Responsive, Model View Controller (MVC), REST, Object-oriented Programming (OOP), Agile Software Development, Functional Programming, Test-driven Development (TDD)


C#, Sass, PHP, HTML, CSS, JavaScript, CSS3, HTML5, TypeScript, ECMAScript (ES6), Java, Groovy, XML/XSLT, SQL, Python


JSON, PostgreSQL, MySQL, Databases, MongoDB, Database Modeling, RDBMS, Amazon S3 (AWS S3)


Debian Linux, Android, Windows, Linux, Visual Studio Code (VS Code), Amazon Web Services (AWS)


Front-end, Web Applications, APIs, User Interface (UI), SVG, CSS3 Animation, Web Animation, Algorithms, Procedural Generation, 3D Graphics, Game Development, Computer Graphics, i18n, Charts, PDF Design, User Experience (UX), Mobile First, Multiplayer, UI Toolkits

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