Full Stack .NET Developer (C# / React / TypeScript)

We are looking for 2 x experienced Full Stack .NET Developer with a strong background in C#, .NET, React, TypeScript and modern web application development to join an established e-commerce project.

The ideal candidate is a hands-on engineer who enjoys solving complex technical problems, understanding existing systems and improving application architecture, performance and maintainability.

Location: 100% Remote - Poland Contract: B2B Start Date: ASAP - ideally next week Project: E-commerce / Application Modernisation & Migration Language: Polish & English

Develop, maintain and enhance full-stack applications using C#/.NET, React and TypeScript.

Analyse existing applications, understand business logic and improve legacy codebases.

Support application modernisation, refactoring and migration initiatives.

Identify and resolve performance bottlenecks across frontend, backend and databases.

Design, develop and optimise REST APIs and backend services.

Improve frontend performance, state management and overall user experience.

Optimise SQL queries, database operations and application response times.

Refactor tightly coupled components and improve code structure, scalability and maintainability.

Write clean, testable and reusable code following software engineering best practices.

Collaborate with developers, architects and business stakeholders to deliver high-quality solutions.

Required Skills & Experience

5+ years of commercial software development experience, ideally in full-stack roles.

Strong hands-on experience with C#, .NET / ASP.NET Core.

Strong frontend development experience with React, JavaScript and TypeScript.

Experience with Redux, Redux Toolkit or other state management solutions.

Solid knowledge of REST APIs and backend architecture.

Strong SQL skills, including query optimisation and relational databases.

Practical experience with legacy application modernisation, refactoring or system migrations.

Experience identifying and resolving application performance issues.

Good understanding of software architecture, design patterns, SOLID principles and clean code.

Experience with unit testing, Git and CI/CD practices.

Ability to independently analyse and troubleshoot complex applications.

Strong analytical thinking and problem-solving abilities.

Good communication skills in Polish and English.