Sebastian Koszuta, Developer in Utrecht, Netherlands
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Sebastian Koszuta

Verified Expert  in Engineering

User Experience (UX) Developer

Location
Utrecht, Netherlands
Toptal Member Since
January 9, 2018

Sebastian is a motivated and creative problem solver with excellent communication skills and comprehensive experience. He's devoted to building UIs that exceed expectations and provide an outstanding user experience. It's his pleasure to write code that is reusable, scalable, and easy to maintain, and he eagerly contributes to business analysis with his knowledge and ideas. When working with Sebastian, expect kindness, enthusiasm, and professionalism.

Portfolio

Freelance
JavaScript, React, Vue, D3.js, TensorFlow, Raspberry Pi, WebGL, Three.js...
Crunch.io
React, D3.js, Storybook, Front-end Build Tools, Dashboards, Data Visualization...
IGT - International Game Technology
Git, Jenkins, Bower, Yarn, TypeScript, Babel, Webpack, Less, UI-Router...

Experience

Availability

Part-time

Preferred Environment

React, Vue, Node.js, Jest, Cypress, Gatsby, TypeScript, Dashboards, Data Visualization, Strapi

The most amazing...

...project I worked on was the dashboards module at Crunch. It was a greenfield project which I had the honor of architecting.

Work Experience

Front-end Developer

2020 - PRESENT
Freelance
  • Developed a situation room dashboard with custom D3 visualizations for a major public transport operator.
  • Built dashboards with a drag-and-drop customizable layout for a cyber security risk intelligence provider.
  • Implemented a lightning-fast, responsive, and SEO-optimized website for a sustainable energy transformation think-tank built with Gatsby and Strapi. Gained hands-on experience with GraphQL.
  • Built an autonomous crane controller with a web interface for an art installation in a public space. Designed and implemented the solution based solely on the customer's idea. Successfully predicted and satisfied the customer's needs.
  • Implemented a 360-degree zoomable viewer of high-resolution pictures for the automobile industry. Applied Microsoft Deep Zoom and OpenSeadragon.
  • Built an interactive remote musical performance experience with the use of TensorFlow machine learning models for pose recognition and WebSockets.
  • Implemented interactive visual experiences for the web involving TensorFlow machine learning models, WebGL, and custom OpenGL shaders.
Technologies: JavaScript, React, Vue, D3.js, TensorFlow, Raspberry Pi, WebGL, Three.js, Python, Gatsby, Strapi, Cube.js, OpenSeadragon, Raspberry Pi 3 GPIO, Arduino, WebSockets, Storybook, React Native, Express.js, Fastify, TypeScript, Dashboards, Data Visualization, REST, API Integration, Interactive Dashboards, Amazon Web Services (AWS), Tailwind CSS, UI Testing, GraphQL, Internet of Things (IoT), Design, Responsive Web Design (RWD), User Interface (UI), Art, Git, NPM, REST APIs, Node.js, Amazon S3 (AWS S3), Figma, User Experience (UX), GitHub, Agile Software Development, React Router, PostgreSQL, CSS, Styled-components, MacOS, Lodash, Material UI, JSON Web Tokens (JWT), HTML, Front-end Development, Full-stack Development, Google Maps API, SCSS, Front-end, Full-stack, Charts, Software Architecture, CSS3, APIs, SaaS, Software as a Service (SaaS), Web Development

Front-end Developer

2018 - 2020
Crunch.io
  • Developed a SaaS data analytics platform for the market research industry with a strong focus on user experience.
  • Architected and implemented a dashboard builder, including a drag-and-drop layout, resizable tiles, customizable visualizations (colors, dimension show/hide, dimension reorder, label editing, axis rescaling), dynamic filtering, and branding.
  • Proposed and implemented architectural solutions to migrate from AngularJS to React.
  • Proposed and implemented build tool reconfiguration to achieve faster build times and optimize production package size.
  • Configured Cypress E2E testing and integrated it with the company's CI pipeline.
  • Took part in recruitment by contacting and interviewing candidates.
  • Worked remotely, in a globally distributed team.
Technologies: React, D3.js, Storybook, Front-end Build Tools, Dashboards, Data Visualization, REST, API Integration, Interactive Dashboards, Analytical Dashboards, UI Testing, Cypress, Webpack, E2E Testing, Plotly, Plotly.js, TypeScript, Responsive Web Design (RWD), User Interface (UI), JavaScript, Git, NPM, REST APIs, Node.js, OAuth 2, User Experience (UX), GitHub, Agile Software Development, Redux, React Router, CSS, Styled-components, MacOS, Lodash, JSON Web Tokens (JWT), HTML, Front-end Development, SCSS, Front-end, Charts, React Redux, Software Architecture, CSS3, APIs, SaaS, Software as a Service (SaaS), Web Development

Front-end Developer

2015 - 2017
IGT - International Game Technology
  • Developed a comprehensive back office application for state lotteries. It encompassed all lottery operations, from managing relationships with ticket resellers to reward payouts.
  • Implemented forms and data grids with responsive layouts and robust data validation.
  • Proposed and initiated the refactoring of stylesheets across the whole application and introduced a style guide.
  • Redesigned and implemented the authentication module from scratch.
  • Proposed and implemented build tool reconfiguration to achieve faster build times and optimize production package size.
  • Migrated the app from Gulp and Babel to Webpack and TypeScript (refactoring and configuration).
  • Implemented customizable KPI dashboards for users of the back-office application.
  • Worked on-site with the state lottery of North Carolina (our customer) during the deployment of our new product. Provided the customer with necessary technical support.
Technologies: Git, Jenkins, Bower, Yarn, TypeScript, Babel, Webpack, Less, UI-Router, Angular Material, Front-end Build Tools, Dashboards, REST, API Integration, UI Testing, Responsive Web Design (RWD), User Interface (UI), JavaScript, NPM, REST APIs, User Experience (UX), Agile Software Development, Bootstrap, Jira, CSS, MacOS, Lodash, HTML, Front-end Development, SCSS, Front-end, Software Architecture, CSS3, APIs, SaaS, Software as a Service (SaaS), Web Development

Front-end Developer

2012 - 2015
Showroom
  • Developed an eCommerce platform for independent fashion designers. The platform quickly became its market leader, and our task was to scale the technology up accordingly.
  • Architected the front-end of the customer-facing website at Showroom.pl.
  • Developed a custom eCommerce management system. It involved brand relationship management tools, custom statistics, shipping company API integration, stock management, etc.
  • Promoted to team leader in August 2014. Managed a team of three front-end developers.
  • Configured front-end build tools and developed core modules such as Auth, routing, or API communication services.
  • Integrated with Facebook OAuth and UPS Shipping API.
Technologies: Git, Bootstrap, PHP, Yeoman, Grunt, Bower, jQuery, Sass, UI-Router, REST, API Integration, Responsive Web Design (RWD), User Interface (UI), JavaScript, NPM, REST APIs, OAuth, Single Sign-on (SSO), User Experience (UX), Agile Software Development, CSS, Lodash, HTML, Front-end Development, Front-end, eCommerce, CSS3, APIs, SaaS, Software as a Service (SaaS), Web Development

Intern Front-end Developer

2011 - 2012
Orange Labs
  • Designed and developed an online conferencing Flash application and an accompanying website.
  • Integrated the Flash app with a Wowza media streaming server.
  • Developed a Flash module that allowed the creation and live-streaming of vector and bitmap content for remote users.
  • Integrated an SMS getaway as part of a new feature for the website.
Technologies: CSS, HTML, Wowza, SQL, PHP, Flash, API Integration, User Interface (UI), JavaScript, User Experience (UX), Front-end Development, Front-end, Web Development

Lottery Management System

An enterprise back-office SPA for state lotteries. Working on this project was an amazing and valuable experience. I learned several new technologies (e.g. ES6, Webpack) and how to deal with challenges of scalability and performance in the cases of complex, enterprise applications.

Showroom

Showroom is the leading independent fashion eCommerce platform in Poland. I was responsible for the front-end of both the website and its back-office application.
2020 - 2023

Bachelor of Fine Arts in Fine Arts

HKU University of the Arts - Utrecht, The Netherlands

2009 - 2014

Bachelor's Degree in Information Technology

Polish-Japanese Academy of Information Technology - Warsaw, Poland

Libraries/APIs

React, React Router, jQuery, Node.js, D3.js, Lodash, REST APIs, Vue, TensorFlow, WebGL, Three.js, Google Maps API, Plotly.js, React Redux

Tools

GitHub, Webpack, Git, Babel, NPM, Grunt, Flash, Wowza, Bower, Yeoman, Jenkins, Redux Thunk, Jira, OpenSeadragon, Front-end Build Tools, Plotly, Figma

Frameworks

Jest, Redux, Bootstrap, Material UI, Yarn, Angular Material, UI-Router, JSON Web Tokens (JWT), Tailwind CSS, Cypress, Cube.js, React Native, Express.js, Fastify, OAuth 2

Languages

HTML, CSS, JavaScript, CSS3, TypeScript, Sass, Less, GraphQL, SCSS, PHP, SQL, Python, Java

Paradigms

REST, Responsive Web Design (RWD), Agile Software Development, E2E Testing

Storage

PostgreSQL, MySQL, Databases, Amazon S3 (AWS S3)

Platforms

MacOS, Raspberry Pi, Raspberry Pi 3 GPIO, Arduino, Amazon Web Services (AWS)

Other

Styled-components, Front-end Development, Front-end, Data Visualization, API Integration, Dashboards, Interactive Dashboards, Analytical Dashboards, UI Testing, User Interface (UI), Art, User Experience (UX), APIs, SaaS, Software as a Service (SaaS), Web Development, Full-stack Development, Strapi, eCommerce, Full-stack, Design, Gatsby, Creativity, Aesthetics, Communication, Software Development, Multimedia, WebSockets, Storybook, Internet of Things (IoT), OAuth, Single Sign-on (SSO), Charts, Software Architecture

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