End-to-end work on e-commerce storefronts

UX/UI designer and front-end developer specializing in custom theme design, theme development and ongoing storefront support for e-commerce platforms. Based in Poland.

Available now – full-time, contract, or project work

Jarosław Karnas – UX/UI designer and front-end developer

Contact

Use the contact form or send a message to info@jaroslawkarnas.com / LinkedIn

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Adobe
Adobe Certified Expert

Adobe Commerce Front-End Developer

Issued by Adobe – 24 Mar 2023 · renewed, valid through 2 Oct 2027

Adobe’s expert-level certification for the Adobe Commerce (Magento 2) storefront layer. The exam covers theme structure and inheritance, layout XML, templates, blocks and view models, LESS-based styling, and translations – together with the front-end JavaScript stack: RequireJS modules, Knockout bindings, and UI components.

It also covers checkout customization, front-end caching behaviour, and the debugging workflow used when extending a live storefront without breaking upgrade paths.

Verify on Adobe
CXL
CXL Certified

Conversion Optimization Minidegree

Issued by CXL – 16 Oct 2025

CXL's Conversion Optimization Minidegree is a 20-course program taught by senior CRO practitioners. It covers the full experimentation workflow – conversion research using analytics, heatmaps, session recordings, surveys, and user testing; heuristic and funnel analysis to locate friction; data-backed hypothesis building and test prioritization; and running statistically valid A/B tests with correct result interpretation.

It also covers digital psychology and persuasion, landing page optimization, and conversion copywriting.

Verify on CXL

Expertise:

From Figma mockups to production-ready code

UX/UI design combined with front-end development for online stores. New themes, as well as day-to-day maintenance and growth of an existing store – new features, template iterations, content updates and marketing campaigns, conversion and performance optimization.

Adobe Certified Expert Hyvä Official Partner

UX/UI Design

User experience and interface design for e-commerce storefronts. Information architecture, wireframes, interactive prototypes, and design systems – built with usability, accessibility, and conversion in mind.

Front-End Development

Implementation of production-ready interfaces in clean, maintainable code. Custom themes and components for e-commerce platforms – with attention to performance and SEO.

Ongoing Support & Optimization

Continuous improvement and day-to-day maintenance of live online stores – refining conversion, performance, and user experience based on data, feedback, and business priorities.

Selected project:

Roban

New - July 2026

Magento 2 / Hyvä storefront, designed and built end to end

End-to-end UX, UI, and front-end development for a Magento 2 / Hyvä storefront, built for Roban, the official Polish importer of Düfa and Profitec paints from German manufacturer Meffert AG Farbwerke. The project covered the complete storefront, from UX discovery and interface design to a production-ready Hyvä theme.

  • Reduced catalog size by 70% through configurable products, improving both UX and product management.
  • Product-specific features built from user research, including custom paint calculators.
  • Mobile Lighthouse performance score improved by 65%.
  • Magento 2
  • Hyvä Theme
  • Hyvä UI
Visit roban.com.pl
https://roban.com.pl
Roban storefront – mobile view

Selected project:

ABCLeg

Custom Magento 2 theme built on Magento Blank

Custom Magento 2 theme development for a Danish retailer of educational toys and learning materials, rebuilding the storefront as a fully responsive theme while preserving the existing visual identity.

  • Live since 2019 with ongoing storefront support.
  • One custom theme powering three Magento storefronts: ABCLeg, Legebutikken, and Edutoys.
  • New pages and features implemented while maintaining a consistent brand experience.
  • Magento 2
Visit abcleg.dk
https://abcleg.dk
ABCLeg storefront – desktop view
ABCLeg storefront – mobile view

Selected project:

Bargain Hardware

Custom Magento 2 theme built from Figma designs

Custom Magento 2 storefront developed from client-provided Figma designs for a UK supplier of refurbished enterprise hardware, delivered as a fully responsive theme in 2024.

  • Pixel-perfect implementation of the client’s Figma designs for desktop and mobile.
  • Responsive intermediate breakpoints designed in code during development.
  • Multi-language and multi-currency support.
  • Magento 2
Visit bargainhardware.co.uk
https://bargainhardware.co.uk
Bargain Hardware storefront – desktop view
Bargain Hardware storefront – mobile view