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Bartłomiej Czyż

Senior Frontend Engineer

Design systems · Developer experience · Front-end architecture · AI-assisted delivery

Summary

Senior front-end engineer with 17 years of experience, the last decade in React. I specialise in design systems, developer experience, and front-end architecture - the foundations that let product teams ship faster and more consistently. At Equals Money I designed and led the company-wide design system from PoC to multi-product adoption, introduced Turborepo, initiated the move to React Query, and built visual-regression infrastructure on top of lost-pixel. I own projects end-to-end, mentor the engineers around them, and care equally about clean code and the systems that keep code clean over time.

Highlights

  • Designed and led Equals Money’s first cross-product design system from PoC to multi-product adoption - now powers the flagship web app, the mobile app, and several smaller products.
  • Modernised the Equals Money front-end platform - introduced Turborepo, initiated the move from Redux/Context to React Query, and built visual-regression testing on top of lost-pixel.
  • Heavy AI-assisted development (Claude Code, Codex) on personal projects, including the open-source ai-profiles macOS app.
  • Mentor and code-reviewer for engineers from junior to senior at four companies; ran a 6-month internal training programme at Hemmersbach.
  • Speaker at DrupalCamp Wrocław and meet.js Wrocław.
  • Solo-shipped slubnegry.pl/bingo - a live, revenue-generating side project.

Experience

  1. Aug 2022 - Present

    Senior Frontend Developer

    Equals MoneyLondon, United Kingdom (remote)

    • Designed and led Equals Money’s first cross-product design system. Took it from a personal PoC through team adoption; mentored contributing engineers; unified the visual language, raised accessibility, and made adding new white-label brands a fraction of the previous effort. Now powers the flagship web app (app.equalsmoney.com), the mobile app, and several smaller products.
    • Introduced Turborepo to orchestrate the monorepo, simplifying shared-package workflows for the team.
    • Initiated the migration from Redux/Context to React Query for server state, setting the patterns the team adopted across the codebase.
    • Built the visual-regression testing infrastructure for the design system and main app on top of lost-pixel (OSS), with custom orchestration - eliminated whole classes of silent visual regressions.
    • Mentored engineers in and around the design system; ran code reviews and architectural design sessions.
    • Interviewed candidates for front-end roles.
    • NextJS
    • TypeScript
    • react-query
    • vanilla-extract
    • shadcn
    • styled-components
    • NodeJS
    • Jest
    • Cypress
    • lost-pixel
    • Turborepo
    • Claude Code
    • Codex
  2. Mar 2020 - Jul 2022

    Senior Frontend Developer

    AdverityVienna, Austria (remote)

    • Shipped components into the company-wide design system used across 3 products - built new components, hardened existing ones, and fixed bugs as the system scaled.
    • Contributed to product development alongside design-system work.
    • React
    • TypeScript
    • NextJS
    • react-query
    • XState
    • NodeJS
  3. Jan 2019 - Mar 2020

    Senior Full Stack Developer

    Software BrothersWrocław, Poland

    • Led a 3-person team building front-ends for City Pantry (Just Eat for Business).
    • Designed and built the API for Bussr in Node.js / NestJS.
    • Angular 7
    • NodeJS
    • NestJS
    • Docker
    • Kubernetes
    • MongoDB
    • Google Cloud
  4. Nov 2017 - Dec 2018

    In-house Software Development Trainer / Team Leader

    HemmersbachWrocław, Poland

    • Designed and ran a 6-month internal training programme for junior web developers (JavaScript, PHP, React/Redux, Symfony 4).
    • Led a 10-engineer team; owned code quality and UX.
    • Built internal applications end-to-end including the Docker/Jenkins environment.
    • TypeScript
    • React
    • Redux
    • MaterialUI
    • PHP 7
    • Symfony4
    • Docker
    • Jenkins

Earlier roles

  1. Sept 2017 - Oct 2017

    Senior Software EngineerTietoAngular / .NET, healthcare

  2. Sept 2014 - Aug 2017

    Full-stack Game DeveloperGame FactoryUnity3D, PHP/Symfony, Java, phaser.js

  3. Sept 2013 - Sept 2014

    Web DeveloperFreedomesPHP/Symfony2, WordPress

  4. Dec 2009 - Sept 2013

    Software DeveloperS.P.L.S. MedicusC++, PHP, PostgreSQL

  5. Jan 2007 - Dec 2009

    FreelancerFreelanceHTML / JavaScript / PHP

Projects

  • slubnegry.pl/bingo

    Polish wedding-games platform. Live, revenue-generating, built solo end-to-end. Bachelorette-games product line in development.

  • ai-profiles

    Open-source macOS app to run multiple Claude and Codex accounts on one Mac - generates isolated per-profile launchers and CLI wrappers so each account’s credentials, history, and settings stay separate. Built solo in Tauri (Rust + TypeScript).

  • Polish stock-market analysis app

    Private side project; uses AI agents to analyse market data and inform decision-making. Built solo, run locally.

  • czyz.it

    This site. Next.js 16 / React 19 / Sanity, custom design system, MDX-driven blog.

I lean on AI heavily in personal work - for coding, code review, and as a research/decision-making layer in my own apps.

Skills

Primary
  • TypeScript
  • React
  • NextJS
  • react-query
  • vanilla-extract
  • shadcn
  • styled-components
  • Cypress
  • Playwright
  • Jest
  • lost-pixel
  • Turborepo
  • NodeJS
  • Claude Code
  • Codex
Strong
  • XState
  • Loki
  • Docker
  • Kubernetes
  • NestJS
  • Jenkins
Languages
  • TypeScript
  • JavaScript
  • PHP
  • C
  • C++
  • C#
  • Java
  • Bash
Databases
  • PostgreSQL
  • MongoDB
  • MySQL
  • SQLite
Legacy
  • Angular
  • AngularJS
  • Symfony
  • Drupal
  • jQuery
  • Unity3D
  • WordPress
  • MaterialUI
  • Twitter Bootstrap
  • SASS
  • gulp.js