Senior Fullstack Developer .NET + React

We are looking for a Fullstack .

NET Developer to work on the development of business applications in an Agile environment. The role combines backend development in C#/.

NET, frontend implementation in React 18+, and analysis/improvement of existing code, including legacy components.

This position is a good fit for someone who enjoys working closely with a delivery team, cares about code quality, and can contribute not only to implementation but also to solution design.

Key responsibilities

• Develop software in C#/.

NET based on technical and functional documentation.

• Implement frontend features in React.
• Analyse, maintain, and extend existing code, including legacy code.
• Contribute to solution architecture and technical design.
• Debug, profile, and analyse application performance.
• Collaborate closely with the delivery team: Testers, Analysts, and Product Owner.
• Work in Agile methodologies, especially Scrum.
• Ensure code quality, maintainability, and alignment with development best practices.

Requirements

• Minimum 5 years of experience developing applications in .

NET.

• Minimum 3 years of experience developing applications in React.
• Very good knowledge of C# and the .

NET ecosystem:

• .

NET Framework,

• .

NET Standard,

• .

NET Core,

• .

NET.

• Experience with React 18+.
• Strong debugging, profiling, and performance analysis skills.
• Knowledge of DDD, Clean Code, and SOLID principles.
• Understanding of architectural patterns and asynchronous communication.
• Good knowledge of T-SQL and SQL Server Management Studio.
• Experience working with Visual Studio.
• English at B2 level or higher.
• Fluent Polish.

Nice to have

• Experience building views for mobile applications.
• Experience developing applications for the financial sector.
• Test automation experience, e.g. Postman, Playwright.
• Knowledge of WCAG accessibility standards.