.NET Backend Developer (SQL Server)

Quick Facts

• Role: .NET Backend Developer (SQL Server)

Description

Develop and modernize backend services for an EDI / e-invoicing platform processing large volumes of documents. You will work across C#/.NET service code and SQL Server (T-SQL, performance, transactions) to ensure reliability and efficiency in production. You will also implement integrations, improve code quality with tests and reviews, and support L3 production issues.

Responsibilities

• Design, implement, and evolve key .NET backend services (document processing/mapping, electronic signing, and transport integrations AS2/AS4/SFTP/Peppol)
• Build and modify SQL Server database logic (stored procedures, query optimization) and integrate .NET services with the database layer
• Resolve complex production problems as L3 support, analyzing and fixing root causes in document processing, integrations, and performance
• Modernize the platform, including migration from .NET Framework to current .NET versions and evolution of Windows Services
• Participate in architecture reviews and present/iterate on platform solutions
• Improve code quality with unit/integration tests, code review, and technical documentation

Requirements

• University degree
• Min. 3 years (regular) or 5 years (senior) commercial backend experience in C#/.NET in production environments
• Very good practical knowledge of C# and .NET, including async programming, multithreading, memory, and resource management
• Practical experience with MS SQL Server and T-SQL: stored procedures, transactions, isolation levels, and basic execution plan analysis
• Practical experience building APIs (REST), SOAP/WCF services, encryption mechanisms (TLS, certificates), and knowledge of Windows Services architecture
• Practical Git experience, CI/CD processes, and working with distributed/service-based architectures
• Practical approach to AI assistants (e.g., Copilot, Claude Code): delegate tasks and critically verify generated code
• Analytical thinking and curiosity to determine root causes
• Independence and responsibility for end-to-end solutions (from development to production support) and ability to work in a team
• English level B2 for communication and reading technical documentation

Benefits

• Private medical care via Allianz
• Cafeteria system (e.g., Multisport card funding or spending on culture, rest, and sport)
• Hybrid work model after onboarding (2 days remote, 3 days in the office)
• Access to advanced AI tools and Google Workspace, plus internal AI-driven development training
• Unique project scale: SaaS system with 4 instances processing EDI and e-invoicing documents
• Work with experienced domain experts; influence architecture with collaboration across IT Architecture and Platform Transformation
• Professional development and real impact on business decisions
• Bike amenities and parking for those commuting by car