Backend Developer

O projekcie: We are SIENN Living Online Technology! Let’s grow with us! Do you want to be a part of something meaningful? We are working on an international project in the financial sector for a Dutch Client specializing in audits, accounting, payroll, HR, and tax advisory. Project Information: We are supporting the development and modernization of an existing accounting application. Role: As a Backend Developer, you will: - Build and modernize backend services using ASP .NET Core MVC and .NET 8+ - Participate in migration to Microsoft Azure - Ensure code quality and scalability - Collaborate with international teams Technology stack: - ASP .Net Core MVC, .Net 10, C# - Azure - Entity Framework - Docker - Git, MS SQL Server What we offer: - B2B rate: 90 - 125 PLN/h - Work in an international project environment - Access to international training and certifications (e.g. Microsoft MCP) - Opportunities for professional development and knowledge sharing - Possibility to access optional benefit platforms (medical care, sports card, insurance, language courses) - Collaborative and supportive project environment Wymagania: Requirements - Strong experience with C# and ASP.NET Core - Commercial experience with .NET (preferably .NET 8+) - Experience in modernizing legacy applications (ASP.NET Framework 4.8 / WebForms / WCF) and migrating them to modern architectures (.NET 10) - Solid experience in designing and building REST APIs and service-based architectures (API-first, domain-driven design) - Good knowledge of MS SQL Server / Azure SQL - Hands-on experience with Microsoft Azure, especially: -          Web Apps -          Container Apps -          Service Bus -          Key Vault - Strong analytical skills and ability to work independently - Team player with experience working in an Agile / Scrum environment - Proactive mindset with a focus on continuous improvement and system modernization - Fluent English (spoken and written) Nice to have: - Experience with Docker (containerization) is a strong plus - Experience in upgrading legacy systems - React.js and experience in ERP environments