KATARZYNA KOWALCZYK-MIELCAREKSOFTWARE ENGINEER

01/Home

SOFTWARE ENGINEER

Frontend interfaces and systems, built from first idea to working product.

A software engineer who owns the full path: frontend architecture, cloud infrastructure and the user experience that ties them together — for crypto, AI and enterprise teams.

Based in Warsaw --:-- WARSAW

[ Let's talk ]

02/Experience

ACTIVE 01 / 04

Experience,
shaped as systems.

Product, infrastructure and interface work across crypto, AI and enterprise, resolved as one connected system.

[ 2022–NOW · REACT · REACT NATIVE
PRODUCT · INTERFACE · BUILD ]

Safello

Senior Frontend · Crypto

Owns frontend architecture end-to-end — React & React Native integrated with AWS infrastructure — for Sweden's leading crypto brokerage.

↗

Stimy AI

Principal Frontend · AI Product

Sole engineer to CEO/CTO — took an AI tutor app from concept to App Store launch, contributing to a $425K pre-seed raise.

↗

Xfaang

Frontend · Software Studio

Tested, responsive web and mobile for real clients.

↗

Accenture

Software Engineer · Enterprise

UI components and prototypes for an international team.

↗

03/How can I help you?

IN FOCUS 01 / 04

Interfaces people see.
Systems that make them work.

I care about both: the surface people touch and the structure that keeps it fast and stable.

End-to-end ownership

From architecture to production — not just the UI layer.

React & React Native

Frontend depth backed by cloud infrastructure and system design.

Tested & maintainable

Tested, scalable systems built to survive contact with real users.

User-first decisions

UX and interaction choices measured by retention, not aesthetics.

[ FRONTEND ]

Interfaces, rhythm, hierarchy and interaction that make a product clear.

[ ENGINEERING ]

Logic, architecture, cloud infrastructure and performance that keep it stable in production.

TypeScriptReactNext.jsReact NativeiOS DevelopmentNode.jsMicroservicesAWSTailwindCSSUXAI-assisted developmentVibe codingLLM integrationPlaywrightProblem solvingSystem design

04/About

SINCE 2022

One line from engineer to frontend developer.

[ ENGINEER FRONTEND ]

After years as a civil and environmental engineer, with a detour through astrophysics, I found my home in code. Since then I've built React and React Native products end-to-end — from cloud infrastructure to App Store launches — for international teams, from crypto to AI.

I care about owning problems end-to-end: architecture, infrastructure and the user experience that ties them together. I've worked directly with founders to help take a product from idea to funded company, and I mentor the people around me along the way.

SkydivingPolish national team

Sport climbing10+ years

Travel50+ countries · Twins oN Tour

LanguagesPolish · English · French

05/Contact

OPEN TO WORK

Let's build
something precise.

For frontend, product and engineering work that needs clear direction and end-to-end ownership.

Start a conversation ↗ LinkedIn ↗

KATARZYNA KOWALCZYK-MIELCAREK · WARSAW PRIVACY/COOKIES/kowalczyk.mielcarek@gmail.com