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

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.

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Experience Level

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.

Education

BSc Computer Science at University College London
January 1, 2012 - January 1, 2016

Qualifications

Microsoft Certified: Azure Developer Associate
January 11, 2030 - May 26, 2026
Microsoft Certified: Azure Fundamentals
January 11, 2030 - May 26, 2026

Industry Experience

Software & Internet, Computers & Electronics, Professional Services, Media & Entertainment