About this roleFor 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 glanceStart: ASAP or by agreementContract: Contract, full-time Setup: Hybrid, 3 days remote and 2 days on-site in MannheimWorking language: English (German is a plus)Your tasksDesign, develop, test and maintain scalable applications in C# and the .NET ecosystemWrite clean, well-documented code following Clean Architecture and the team’s coding standardsWork test-driven (TDD) and strengthen a culture of automated testingBuild robust multi-threaded solutions using locking, interlocking and parallelism in .NETTurn business requirements into technical solutions together with product owners, architects and cross-functional teamsReview code and give constructive feedback to keep quality and consistency highMentor junior and mid-level developers and provide technical guidanceIdentify and drive improvements in architecture, performance, reliability and maintainabilityTroubleshoot and resolve complex issues across a distributed software stackContribute to CI/CD and modern delivery practicesYour profileMust haveDeep, hands-on knowledge of C# 14 and modern .NETSeveral years of experience with multi-threaded programmingSeveral years of experience with high-volume in-memory data processingSolid experience designing and implementing RESTful APIsStrong command of OOP, SOLID, Clean Code, multi-layer architecture and TDDPractical exper