Senior Fullstack .NET Developer (f/m/x)

We are looking for a highly experienced Fullstack .NET Developer with strong React skills to join a long‑term project delivered by Sii for an international organization recognized for its advanced laboratory and diagnostics technologies. You will work on the development and modernization of complex systems, including legacy monolithic applications and WPF components, while contributing to new features built on ASP.NET Core and modern JavaScript frameworks.

The role is hybrid, with 2–3 days per week in our Wrocław office.

If you're ready for your next big challenge — apply now!

Your tasks

• Design, develop, and maintain fullstack applications using ASP.NET Core, C#, and React
• Modernize and refactor existing monolithic systems, ensuring performance and scalability
• Implement and enhance UI components, including work with WPF where necessary
• Collaborate with cross‑functional teams on architecture, code reviews, and technical direction
• Troubleshoot, optimize, and ensure high-quality, testable, and maintainable code