New Monday GmbH

Senior Software Engineer C# / .NET (m/w/d)

Mannheim, Germany full-time Mid Salary not listed
full-time Mid level Technology & IT Curated
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About the role

About this role
For our client, a global leader in metrology and process control for semiconductor manufacturing, we are looking for a Senior Software Engineer C# / .NET (m/w/d) for a permanent position.
The team is based in Mannheim and has more than 25 years of experience building high-precision measurement systems. Their software looks down to the atomic level and turns what it sees into actionable data for the production of the world’s most advanced computer chips.
In this role you will design, build and maintain distributed software where performance, concurrency and reliability matter. You will also help shape how the team builds that software.
At a glance
Start: ASAP or by agreement

Contract: Contract, full-time

Setup: Hybrid, 3 days remote and 2 days on-site in Mannheim

Working language: English (German is a plus)

Your tasks
Design, develop, test and maintain scalable applications in C# and the .NET ecosystem

Write clean, well-documented code following Clean Architecture and the team’s coding standards

Work test-driven (TDD) and strengthen a culture of automated testing

Build robust multi-threaded solutions using locking, interlocking and parallelism in .NET

Turn business requirements into technical solutions together with product owners, architects and cross-functional teams

Review code and give constructive feedback to keep quality and consistency high

Mentor junior and mid-level developers and provide technical guidance

Identify and drive improvements in architecture, performance, reliability and maintainability

Troubleshoot and resolve complex issues across a distributed software stack

Contribute to CI/CD and modern delivery practices

Your profile
Must have
Deep, hands-on knowledge of C# 14 and modern .NET

Several years of experience with multi-threaded programming

Several years of experience with high-volume in-memory data processing

Solid experience designing and implementing RESTful APIs

Strong command of OOP, SOLID, Clean Code, multi-layer architecture and TDD

Practical experience with automated testing: unit tests, component tests, mocking

Good working knowledge of UML

Proven experience in hardware-related software development

Degree in Computer Science, Software Engineering, Physics or a related field

Excellent English; you work well in international, cross-functional teams

Nice to have
Real-time systems, hardware integration or optical sensor data processing (strong plus)

Legacy modernization, such as migrating a monolith to distributed, service-oriented systems or microservices

Distributed system design: event-based and object-based architecture, fault detection, causality methods, fault tolerance

Relational database design

Front-end development with .NET MAUI

German language skills

What we offer
A contract position at a global technology leader in a growing industry

Technically demanding work at the intersection of software, hardware and physics

A hybrid setup with 3 days remote per week

An international team that values clean engineering and code quality

Real influence on architecture, and the chance to mentor other developers

Personal support from us throughout the hiring process

Interested?
Send us your CV with your salary expectations and notice period. Unsure whether you meet every requirement? Apply anyway. We’d rather talk to you than miss a good match.

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Interview prep

Walk in with sharper answers.

Use this as a quick practice sheet before you speak with the employer.

Mid
Technology & IT API integration MySQL Remote Collaboration Senior Software Mid level

Likely questions

  1. Tell us about work you have done that is close to the Senior Software Engineer C# / .NET (m/w/d) role.
  2. How would you approach your first 30 days at New Monday GmbH?
  3. Which of API integration, MySQL and Remote Collaboration have you used recently, and what did it help you achieve?
  4. Describe a time you solved a problem without waiting to be told exactly what to do.
  5. How do you handle busy days, changing priorities, or pressure at work?

Prepare before the call

  • A recent example that proves your experience with API integration, MySQL and Remote Collaboration.
  • One short story with a problem, your action, and the result.
  • Two examples that show the strengths listed on your CV.
  • A clear reason why this role and company interest you.
  • Your availability, preferred work style, and salary expectations.

Ask them

  • What would success look like in the first 90 days?
  • What are the main problems this hire should help solve?
  • How does the team give feedback and measure good work?
  • What does a normal working week look like for this role?
Practice line

I am interested in the Senior Software Engineer C# / .NET (m/w/d) role because I can bring practical experience in API integration, MySQL and Remote Collaboration, learn the team quickly, and contribute to the outcomes New Monday GmbH needs from this hire.

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