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
Job 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