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I am a Senior Frontend Engineer with 8+ years of experience delivering high-quality web applications. I am proficient in HTML5, CSS3, JavaScript, and React, building scalable and performant solutions. I focus on problem-solving, applying solid UI/UX principles, and strong communication to collaborate effectively with international teams. I mentor junior engineers and continuously explore AI-assisted development tools to boost productivity.…I am a Senior Frontend Engineer with 8+ years of experience delivering high-quality web applications. I am proficient in HTML5, CSS3, JavaScript, and React, building scalable and performant solutions. I focus on problem-solving, applying solid UI/UX principles, and strong communication to collaborate effectively with international teams. I mentor junior engineers and continuously explore AI-assisted development tools to boost productivity.

Marcin Deperas

Front-End Developer, Web Developer, Programmer

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I am a Senior Frontend Engineer with 8+ years of experience delivering high-quality web applications. I am proficient in HTML5, CSS3, JavaScript, and React, building scalable and performant solutions. I focus on problem-solving, applying solid UI/UX principles, and strong communication to collaborate effectively with international teams. I mentor junior engineers and continuously explore AI-assisted development tools to boost productivity.…I am a Senior Frontend Engineer with 8+ years of experience delivering high-quality web applications. I am proficient in HTML5, CSS3, JavaScript, and React, building scalable and performant solutions. I focus on problem-solving, applying solid UI/UX principles, and strong communication to collaborate effectively with international teams. I mentor junior engineers and continuously explore AI-assisted development tools to boost productivity.

Available to hire

I am a Senior Frontend Engineer with 8+ years of experience delivering high-quality web applications. I am proficient in HTML5, CSS3, JavaScript, and React, building scalable and performant solutions.
I focus on problem-solving, applying solid UI/UX principles, and strong communication to collaborate effectively with international teams. I mentor junior engineers and continuously explore AI-assisted development tools to boost productivity.

Skills

Experience Level

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Intermediate

Language

English

Advanced

Polish

Fluent

Work Experience

Senior Frontend Engineer at Caspio

August 1, 2024 - October 29, 2025

Building Caspio's next-generation no-code App Designer using React 18, TypeScript, Redux Toolkit, and Redux-Saga; collaborating with .NET microservices to design and integrate REST APIs; driving UI architecture and design consistency through reusable components (Storybook, PrimeReact) and Figma collaboration; ensuring high code quality with TDD, Jest, Cypress, and Playwright; mentoring junior engineers and introducing AI-assisted development tools (Copilot, Cursor) to boost team productivity.

Senior Frontend Engineer at Casumo

January 31, 2024 - January 31, 2024

Developed and maintained two large-scale React + Next.js applications—a public-facing SSR app and a logged-in user portal—across multiple markets, ensuring high performance and consistent UX; led migration to micro-frontend architecture; integrated with REST APIs and cloud services; delivered accessible, responsive UI with Tailwind CSS and collaborated with backend and DevOps to enable seamless deployments.

Full Stack Developer at DAZN Media Poland

March 31, 2022 - March 31, 2022

Built and maintained React.js + Node.js microservice-based applications delivering content to global audiences; designed and optimized high-performance services handling thousands of concurrent requests; collaborated with cross-functional teams to ensure scalable deployments, automated testing, and monitoring in AWS; improved data flows, caching, and reliability.

Full Stack Developer at EPAM Systems

March 31, 2020 - March 31, 2020

Developed full-stack applications using React and .NET, creating responsive UIs and enhancing system capabilities through new REST API features; integrated third-party APIs and client systems to ensure seamless data exchange and reliable performance across environments.

Full Stack Developer at Future Processing

December 31, 2018 - December 31, 2018

Developed and maintained logistics web platform using .NET and JavaScript (jQuery), delivering new features and usability improvements; supported production systems and resolved customer issues to ensure smooth user experience; introduced test automation strategies that improved software quality and reduced release cycle time.

QA Engineer at Future Processing

March 31, 2017 - March 31, 2017

Designed and executed functional and automated tests, improving software performance and reducing manual testing time; reported and resolved defects that significantly lowered customer complaints and boosted overall product quality.