Daniel Sladecek

Senior JavaScript Developer focused on production-grade front-end systems

Architecting scalable, high-performance web applications with expertise in modern JavaScript frameworks. Passionate about clean code and exceptional user experiences.

  • 8+ years of professional experience in front-end development
  • Strong focus on maintainability, performance, and accessibility
  • Production experience on large-scale systems serving millions of users

Skills

Core Stack

  • React
  • Next.js
  • Astro
  • Vue
  • Nuxt.js
  • TypeScript
  • Tailwind

Also Proficient In

  • React Native
  • Node.js
  • Vite
  • Webpack
  • Sentry
  • Flutter
  • Dart
  • Angular
  • GraphQL
  • Cypress
  • Playwright
  • Grafana

Featured Work

Gen Digital

Norton / Avast / AVG

Led front-end development of the checkout application serving millions of Avast and AVG customers. Built an internal Chrome extension for API-driven checkout testing, enabling teams to generate pre-configured product links on the fly. Contributed to account portal development across Norton and Avast brands.

  • React
  • Angular
  • Vue
  • Node.js
E-stránky

Web Builder Platform

Developed and maintained web templates using HTML, CSS, JavaScript, and PHP (Nette), ensuring cross-device responsiveness across legacy and modern layouts. Led the redesign of the administration portal, delivering a refreshed interface and improved workflows. Provided direct customer support for custom CSS, JavaScript, and HTML modifications.

  • HTML
  • CSS
  • JavaScript
  • PHP
Earthfluence

Agency & E-commerce Projects

Built agency and company websites from the ground up using Nuxt.js, including digitalgreensagency.eu and earthfluence.cz. Revamped the Shoptet e-commerce template for noother.cz, managing the migration from a DigitalOcean/Dokku infrastructure with Snipcart to a full Shoptet integration. Assisted with Shopify storefront styling for Tabsta.

  • Nuxt.js
  • Vue
  • Shoptet
  • Shopify
Digital Greens Agency website

Selected Experiments

Personal projects used to explore new tooling and patterns outside of day-to-day work.

Journey Challenge app

Journey Challenge

Track your progress on a chosen route while racing against friends and family. Your journey is displayed on an interactive map powered by the TomTom Navigation API. Built with Next.js and deployed on Vercel, the app accepts URL parameters for names, distances, colors, and route waypoints.

  • Next.js
  • React
  • TomTom API
  • Vercel
Calorie Budget app

Calorie Budget

A simple yet effective calculator that helps you manage your diet by computing a weekly calorie budget. If you slip up one day, the app adjusts your remaining intake to keep you on track. Built with React and Vite as a Progressive Web App with local storage, localization, and interactive graphs.

  • React
  • Vite
  • PWA
  • Vercel

About

I'm a senior front-end developer with 8+ years of experience building production systems at scale. I value pragmatic decisions over trends and care deeply about code quality, performance, and clear communication within teams.

What I bring to the table

  • Front-end engineering treated as a full-fledged discipline
  • Ability to maintain and evolve an existing codebase
  • Focus on long-term quality over short-term fixes
  • Calm, straightforward communication within the team

Contact

Get in touch if you:

  • are looking for a senior front-end developer for your product team
  • want to discuss a specific role or collaboration
  • need an experienced front-end engineer for an existing system
Get in Touch