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I'm Marcin Kowalski, a Senior Software Engineer based in Warsaw, Poland, with 8+ years delivering robust web applications using ASP.NET Core, C#, React, and Azure. I specialize in REST API development, SQL Server integration, and scalable frontend solutions within distributed teams. I thrive on turning complex requirements into scalable cloud-based architectures and collaborating with stakeholders to plan and deliver reliable software. Whether working independently or with cross-functional teams across Europe, I drive CI/CD, cloud deployment workflows, and performance optimizations to improve reliability and maintainability. In my free time I mentor junior developers, contribute to internal tooling, and continually explore new technologies to keep our solutions future-proof.…I'm Marcin Kowalski, a Senior Software Engineer based in Warsaw, Poland, with 8+ years delivering robust web applications using ASP.NET Core, C#, React, and Azure. I specialize in REST API development, SQL Server integration, and scalable frontend solutions within distributed teams. I thrive on turning complex requirements into scalable cloud-based architectures and collaborating with stakeholders to plan and deliver reliable software. Whether working independently or with cross-functional teams across Europe, I drive CI/CD, cloud deployment workflows, and performance optimizations to improve reliability and maintainability. In my free time I mentor junior developers, contribute to internal tooling, and continually explore new technologies to keep our solutions future-proof.

Marcin Kowalski

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

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I'm Marcin Kowalski, a Senior Software Engineer based in Warsaw, Poland, with 8+ years delivering robust web applications using ASP.NET Core, C#, React, and Azure. I specialize in REST API development, SQL Server integration, and scalable frontend solutions within distributed teams. I thrive on turning complex requirements into scalable cloud-based architectures and collaborating with stakeholders to plan and deliver reliable software. Whether working independently or with cross-functional teams across Europe, I drive CI/CD, cloud deployment workflows, and performance optimizations to improve reliability and maintainability. In my free time I mentor junior developers, contribute to internal tooling, and continually explore new technologies to keep our solutions future-proof.…I'm Marcin Kowalski, a Senior Software Engineer based in Warsaw, Poland, with 8+ years delivering robust web applications using ASP.NET Core, C#, React, and Azure. I specialize in REST API development, SQL Server integration, and scalable frontend solutions within distributed teams. I thrive on turning complex requirements into scalable cloud-based architectures and collaborating with stakeholders to plan and deliver reliable software. Whether working independently or with cross-functional teams across Europe, I drive CI/CD, cloud deployment workflows, and performance optimizations to improve reliability and maintainability. In my free time I mentor junior developers, contribute to internal tooling, and continually explore new technologies to keep our solutions future-proof.

Available to hire

I’m Marcin Kowalski, a Senior Software Engineer based in Warsaw, Poland, with 8+ years delivering robust web applications using ASP.NET Core, C#, React, and Azure. I specialize in REST API development, SQL Server integration, and scalable frontend solutions within distributed teams. I thrive on turning complex requirements into scalable cloud-based architectures and collaborating with stakeholders to plan and deliver reliable software.

Whether working independently or with cross-functional teams across Europe, I drive CI/CD, cloud deployment workflows, and performance optimizations to improve reliability and maintainability. In my free time I mentor junior developers, contribute to internal tooling, and continually explore new technologies to keep our solutions future-proof.

Skills

Experience Level

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Language

English

Fluent

Polish

Intermediate

Chinese

Advanced

Russian

Advanced

German

Intermediate

Work Experience

Senior Software Engineer at Eklib Software

March 1, 2024 - Present

Developed backend services using ASP.NET Core and C# for cloud-based workforce scheduling applications. Worked on React frontend modules supporting real-time operational dashboards and reporting workflows. Designed RESTful APIs integrated with SQL Server through Entity Framework Core. Responsible for Azure App Service deployment configuration and application monitoring activities. Implemented CI/CD pipelines using Azure DevOps to reduce deployment preparation time by 22%. Resolved performance bottlenecks affecting API response times during peak periods. Participated in architecture discussions focused on scalability and long-term maintainability requirements. Collaborated with product stakeholders to refine technical requirements and delivery timelines. Developed reusable frontend components that reduced duplicate interface implementation efforts by 18%.

Senior Software Engineer at Altum Software

December 1, 2019 - February 29, 2024

Developed enterprise applications using ASP.NET Core, React, and SQL Server within Agile delivery teams.

Software Engineer at ThoughtWorks

December 1, 2017 - November 30, 2019

Backend services using C#, ASP.NET Core, and SQL Server for enterprise financial applications. Worked on frontend interfaces using Angular and TypeScript in client-facing operational systems. Contributed to REST API integration tasks supporting internal and third-party services. Responsible for maintaining deployment scripts and supporting Azure-hosted application environments. Participated in Agile sprint planning, testing activities, and production issue troubleshooting. Developed automated unit tests using NUnit and supported API validation with Postman.

Software Development Intern at ThoughtWorks

July 1, 2016 - November 30, 2017

Internal tools using C#, ASP.NET MVC, and JavaScript technologies. Supported SQL Server database maintenance and basic API integration activities. Contributed to frontend updates and issue resolution tasks within Agile development teams. Participated in code reviews and software testing activities alongside senior engineers. Gained foundational exposure to cloud deployment and DevOps practices.