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I'm Jan Kowalski, a Senior Full-Stack Engineer with 11 years of experience delivering scalable, high-performance web applications and cloud-based solutions. I excel at bridging frontend and backend teams, mentoring developers, and driving product innovation in fast-paced environments. I have strong expertise across React, Next.js, Node.js, Python, and cloud platforms like AWS, Azure, and GCP, with a proven ability to design robust microservices, integrate complex APIs, and optimize performance end-to-end.…I'm Jan Kowalski, a Senior Full-Stack Engineer with 11 years of experience delivering scalable, high-performance web applications and cloud-based solutions. I excel at bridging frontend and backend teams, mentoring developers, and driving product innovation in fast-paced environments. I have strong expertise across React, Next.js, Node.js, Python, and cloud platforms like AWS, Azure, and GCP, with a proven ability to design robust microservices, integrate complex APIs, and optimize performance end-to-end.

Jan Kowalski

Full Stack Developer, Web Developer, Back-End Developer, +2

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I'm Jan Kowalski, a Senior Full-Stack Engineer with 11 years of experience delivering scalable, high-performance web applications and cloud-based solutions. I excel at bridging frontend and backend teams, mentoring developers, and driving product innovation in fast-paced environments. I have strong expertise across React, Next.js, Node.js, Python, and cloud platforms like AWS, Azure, and GCP, with a proven ability to design robust microservices, integrate complex APIs, and optimize performance end-to-end.…I'm Jan Kowalski, a Senior Full-Stack Engineer with 11 years of experience delivering scalable, high-performance web applications and cloud-based solutions. I excel at bridging frontend and backend teams, mentoring developers, and driving product innovation in fast-paced environments. I have strong expertise across React, Next.js, Node.js, Python, and cloud platforms like AWS, Azure, and GCP, with a proven ability to design robust microservices, integrate complex APIs, and optimize performance end-to-end.

Available to hire

I’m Jan Kowalski, a Senior Full-Stack Engineer with 11 years of experience delivering scalable, high-performance web applications and cloud-based solutions. I excel at bridging frontend and backend teams, mentoring developers, and driving product innovation in fast-paced environments.

I have strong expertise across React, Next.js, Node.js, Python, and cloud platforms like AWS, Azure, and GCP, with a proven ability to design robust microservices, integrate complex APIs, and optimize performance end-to-end.

Skills

Experience Level

Expert

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Intermediate

Intermediate

Work Experience

Senior Full-Stack Engineer at Luxoft

August 1, 2025 - October 2, 2025

Led the design and development of healthcare dashboards and patient engagement portals using React, Next.js and TypeScript, with secure backend integration via Node.js and Python APIs. Implemented role-based authentication and authorization with Firebase Auth, ensuring secure handling of sensitive healthcare data. Integrated RESTful and GraphQL APIs to connect clinical systems with real-time patient data, improving care team efficiency. Developed interactive data visualization features with D3.js and Chart.js, enabling healthcare providers to monitor patient vitals in real time. Optimized performance with server-side rendering, lazy loading and code splitting, reducing load times and improving reliability. Mentored junior engineers, promoted adoption of TDD, and improved code quality through peer reviews.

Senior Full-Stack Engineer at Luxoft

August 1, 2025 - October 2, 2025

Led the design and development of healthcare dashboards and patient engagement portals using React, Next.js, and TypeScript, with secure backend integration via Node.js and Python APIs. Implemented role-based authentication and authorization with Firebase Auth, ensuring secure handling of sensitive healthcare data. Integrated RESTful and GraphQL APIs to connect clinical systems with real-time patient data, improving care team efficiency. Developed interactive data visualization features with D3.js and Chart.js for real-time vitals monitoring. Optimized performance with server-side rendering, lazy loading, and code-splitting, reducing load times and improving reliability. Mentored junior engineers and promoted TDD and code quality through peer reviews.

Senior Full-Stack Engineer at Luxoft

August 1, 2025 - October 2, 2025

Led design and development of healthcare dashboards and patient engagement portals using React, Next.js, and TypeScript, with secure backend integration via Node.js and Python APIs. Implemented role-based authentication and authorization with FirebaseAuth for secure handling of healthcare data. Integrated RESTful and GraphQL APIs to connect clinical systems with real-time patient data, improving care team efficiency. Developed interactive data visualizations with D3.js and Chart.js for real-time vitals monitoring. Optimized performance with server-side rendering, lazy loading, and code-splitting, reducing load times and increasing reliability. Mentored junior engineers, promoted TDD, and improved code quality through peer reviews.

Full-Stack Engineer at Scoro

December 1, 2022 - October 2, 2025

Designed and implemented microfrontend architecture and modular backend services, improving maintainability and scalability across retail and real estate platforms. Built reusable UI component libraries with React and Storybook, ensuring consistency and faster development cycles across distributed teams. Integrated backend services via RESTful and GraphQL APIs, enabling real-time property search and inventory management features. Enhanced performance by reducing bundle size with Webpack and optimizing API queries, cutting page load times by 40% during high traffic. Delivered a real-time inventory alert system powered by Node.js and WebSockets, improving supply chain responsiveness. Led testing strategy improvements with Jest, React Testing Library, and Cypress, increasing overall system reliability.

Full-Stack Engineer at Scoro

December 1, 2022 - October 2, 2025

Designed and implemented microfrontend architecture and modular backend services for retail and real estate platforms. Built reusable UI component libraries with React and Storybook to ensure consistency and faster development across distributed teams. Integrated backend services via RESTful and GraphQL APIs, enabling real-time property search and inventory management. Improved performance by reducing bundle sizes with Webpack and optimizing API queries, cutting page load times by 40% during high traffic. Delivered a real-time inventory alert system powered by Node.js and WebSockets, improving supply chain responsiveness. Led testing strategy improvements with Jest, React Testing Library, and Cypress.

Full-Stack Engineer at Scoro

December 1, 2022 - October 2, 2025

Designed and implemented microfrontend architecture and modular backend services to improve maintainability and scalability for retail and real estate platforms. Built reusable UI component libraries with React and Storybook for consistency and faster development across distributed teams. Integrated backend services via RESTful and GraphQL APIs enabling real-time property search and inventory management. Enhanced performance by reducing bundle sizes with webpack and optimizing API queries, cutting page load times by 40% during high traffic. Delivered a real-time inventory alert system powered by Node.js and WebSockets, improving supply chain responsiveness. Led testing strategy improvements with Jest, React Testing Library, Cypress, increasing overall system reliability.

Junior Full-Stack Developer at SoftwareMind

February 1, 2018 - October 2, 2025

Contributed to the development of a large-scale e-commerce platform, focusing on frontend UI optimization and backend API integrations. Rebuilt core website features with modern JavaScript and Node.js, improving scalability and cross-browser performance. Integrated third-party services such as Stripe (payments), Firebase (auth), and Google Maps API, expanding platform functionality and enhancing user experience. Improved frontend performance by implementing code splitting, lazy loading, and optimized API calls. Supported senior developers with code reviews, database integrations, and testing, gaining full-stack expertise in agile workflows.

Junior Full-Stack Developer at SoftwareMind

February 1, 2018 - October 2, 2025

Contributed to the development of a large-scale e-commerce platform, focusing on frontend UI optimization and backend API integrations. Rebuilt core website features with modern JavaScript and Node.js, improving scalability and cross-browser performance. Integrated third-party services such as Stripe, Firebase Auth, and Google Maps API, expanding functionality and enhancing user experience. Improved frontend performance with code splitting, lazy loading, and optimized API calls. Supported senior developers with code reviews, database integrations, and testing, gaining full-stack expertise in agile workflows.

Junior Full-Stack Developer at SoftwareMind

February 1, 2018 - October 2, 2025

Contributed to the development of a large-scale e-commerce platform, focusing on frontend UI optimization and backend API integrations. Rebuilt core website features with modern JavaScript and Node.js, improving scalability and cross-browser performance. Integrated third-party services such as Stripe, Firebase Auth, and Google Maps API, expanding functionality and enhancing user experience. Improved frontend performance through code splitting, lazy loading, and optimized API calls. Supported senior developers with code reviews, database integrations, and testing, gaining full-stack expertise in agile workflows.