Július Retzer

Front-end developer specializing in React apps in Typescript


Lead Software Engineer ContractRemote

EPAM Systems
  • Assumed ownership and responsibility for the application and new features​
  • Responsible for the deployment process to production​​
  • Initiated the development of automated tests (e2e) and their introduction to the development process​​
  • Implemented crucial web app performance metrics and their tracking via Firebase to measure the long-term impact of the changes on the user experience​​
  • Reduced the total bundle app bundle size by roughly 20% through webpack configuration​​
  • Conceived and implemented a more efficient branching and releasing strategy​​
  • Drafted several technical proposal documents​​
  • Established stricter code quality practices (Typescript, Eslint, Prettier)​​
  • Coordinated major version updates of Node.js and Next.js​​

Technology used:

  • React
  • Typescript
  • Next.js
  • Cypress
  • Jest
September 2020 - present

Priznanie.digital Lead Developer VolunteerRemote


The process of filing the Slovak tax return form is an arduous ordeal. In its current shape, the user is facing a 130+ field form, described by bureaucratic language and with zero user guidance. Many small business owners choose to delegate this task to external accountants for a considerable fee.

Together with other volunteers and slovensko.digital, we designed and developed a simplified wizard-like application called priznanie.digital. It covers the most common use cases with as little effort from the user as possible and calculates all necessary tax information for users to upload to the government web.

The user experience and accessibility was our focus, as we adhered to gov.uk Design System.

Technology used:

  • React
  • Typescript
  • Next.js
  • Cypress (extensive automated test suite testing the correctness of the calculations in various use cases)
  • Jest
  • Github Actions (CI)
  • Vercel/Dokku (deployment)
February 2020 - present

Lab Master / Lecturer Contract


OpenLab is a non-profit education project aiming to dramatically improve IT education in Slovakia by bridging the gap between high schools and the private sector.

My responsibilities include:

  • Creating a safe and free environment for the students to grow professionally and personally
  • Teaching students to independently develop applications using web technologies (HTML, CSS, JS, PHP) and frameworks (Vue, Ionic, Angular, OctoberCMS)
  • Guiding students through the entire app development lifecycle (specification, design, development, testing, deployment) while developing solutions to the real-world problems
  • Mentoring and aiding students to develop the necessary soft skills (teamwork, communication, feedbacking, self-reflection)
  • Development of the syllabus and teaching materials
  • Contributing with ideas to the optimization and viability of the OpenLab project
May 2019 - June 2020

Web Developer Full-timePartially remote

Danske Bank / Danske Bank Bolig

I was a part of a team developing sunday.dk (now moved to danskebank.dk/bolig), a project that helps people to understand their finances better when finding and buying a new home.

My main focus was on the frontend (React, Redux, Typescript, Enzyme, Webpack, Storybook), but I also contributed to the backend (Node, Express, Swagger, Mocha, Sequelize).

I concentrated on bridging the gap between developers and designers, intending to make sure that we share systematic ways to guide and leverage our collective efforts. This lead to the development of our design system that helps us to stay consistent both in the designs and across the implementation.

Stack: React, Redux, Node, Express, Typescript, PostgreSQL, Elasticsearch, AWS

August 2016 - March 2019 (2 years, 8 months)

Web Developer Full-time

Quadric / Feats.co

I was part of a small team building a new social network using Meteor and React as core technologies. The social network eventually became www.feats.co.

Our team:

  • adheres to domain-driven development
  • emphasizes writing accurate specifications in a domain-specific language
  • maintains high test coverage on all levels: e2e, integration (Cucumber/Chimp.js) and unit tests (Karma, Enzyme)
  • implements continuous integration server as part of the build process - always seeks to work with the latest technologies

Stack: React, Meteor, MongoDB, Cucumber, Chimp

February 2016 - June 2016 (5 months)

Junior Web Developer Full-time


Using stickers with QR codes and NFC chips, eDocu brings you the right information on the spot. eDocu is a robust web application based on dockerized microservices using technologies like Node.js, Clojure and MongoDB on the backend and AngularJS on the frontend.

My responsibilities were:

  • development of new features using AngularJS
  • design of basic UI/UX
  • backend services in Node.js
  • migration and utility scripts in Node.js
  • learning from the more experienced

Stack: AngularJS, Node, Express, MongoDB

Feb 2015 - Feb 2016 (1 year)