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Krzysztof Mendroch

@krzysztofmendroch

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I build scalable React and .NET web and mobile applications.

Poland

Message

I've built end-to-end web and mobile applications across React, TypeScript, C#, and .NET, from database and REST APIs through to responsive user interfaces.

At Medius, I developed and maintained 15+ reusable React UI components for a Design System used by 10+ product teams. I managed its release lifecycle, built product-to-product REST APIs, and supported stable production releases through testing and hotfixes.

I also modernized a legacy C# backend from .NET Framework 4.7 to .NET 8 and created a VS Code JWT Viewer extension adopted by 900+ developers. My work included automated testing with NUnit, Selenium, Jest, React Testing Library, and Playwright.

Previously at Optimal IT, I delivered three Android and iOS mobile applications with React, Cordova, and Firebase, taking projects from requirements gathering through publication in the app stores.

Experience

Work history, roles, and key accomplishments

Full-Stack Developer

Medius

Aug 2024 - Apr 2026 (1 year 8 months)

Developed and maintained 15+ reusable UI components as part of a React-based Design System used by 10+ product teams. Managed the complete release lifecycle of the Design System and built REST APIs for product-to-product communication.

React TypeScript Redux .NET 8+C#ASP.NET Core REST APIs Jest React Testing Library Playwright NuGet NPM Azure DevOps

Full-Stack Developer Intern

Medius

Feb 2024 - Jul 2024 (5 months)

Migrated a legacy C# codebase from .NET Framework 4.7 to .NET 8, modernizing backend architecture. Developed a VS Code 'JWT Viewer' extension adopted by 900+ developers and built REST APIs for platform integration.

C#.NET Framework .NET 8+REST APIs NUnit Selenium VSCode Git

Junior Software Developer

Optimal IT

Jul 2022 - Dec 2023 (1 year 5 months)

Developed and deployed 3 mobile applications for Android and iOS using React, Cordova, and Firebase. Managed the full project lifecycle from requirements gathering to publication on Google Play and Apple App Store.