C# and .net developer

Kajenthi@R ED Global - Senior Software Engineer (C#/.NET) - Freelance Contract - Mannheim - Hybrid

We are seeking experienced Senior Software Engineers (C#/.NET) with HW to join a major development project based in Mannheim, Germany.

Location: Mannheim, Germany (2 days per week on-site)

Start Date: 20 November 2026

Duration: Initial 6-month contract (extensions possible)

Language: English only (German not required)

Responsibilities

· Design, develop, test and maintain tool control software in C# and .NET

· Drive modularisation of a mature codebase without destabilising a production system

· Build robust concurrent code: multi-threading, locking and interlocking, parallelism in .NET

· Apply TDD and strengthen automated testing, including tests that touch real hardware

· Conduct code reviews; mentor and coach mid-level developers

· Troubleshoot complex issues across the software and hardware boundary

Must have

· Senior, hands-on C# and .NET on production systems

· Proven engineering experience in a hardware-related development environment — code that has controlled, driven or read from physical equipment

· Object-oriented design, SOLID, design patterns, Clean Code

· Test-Driven Development and ownership of automated test suites

· Multi-threading, locking/interlocking and parallelism in .NET

· Experience refactoring and modularising a long-lived legacy codebase

· Mentoring and code review experience

· English B2 or above. German not required

· Travel-ready for approximately 2 days per week on site in Mannheim, Germany

Strong plus

· Real-time systems and deterministic timing

· Hardware integration: motion control, sensors, actuators, device drivers, instrument interfaces

· Optical sensor data processing: spectroscopy, interferometry, imaging, signal processing

· Domain background in semiconductor, metrology, test and measurement, precision instrumentation, industrial automation or medical devices

· German language

If you're interested by this role, please send me your CV at [email protected]