Safetec GmbH is an independent company of E.ON SE with headquarters in the beautiful city of Heidelberg. Over the past 30 years, Safetec has developed into the market and technology leader in radiation protection and nuclear decommissioning. We provide our customers with expert advice and support throughout the entire life cycle of a nuclear facility, from construction and operation through to dismantling. With around 700 employees, innovative technologies and solutions, we make a decisive contribution to the success of nuclear decommissioning in Ger many. Cutting-edge software products and our ongoing digitalization efforts are at the heart of these solutions, ensuring efficiency, safety and transparency at every step. Are you looking for a new professional challenge in an industry with secure future prospects and high social relevance? We are looking for a Backend API Developer (C#, .NET) to support our development team in Heidelberg as soon as possible. Stability: You will receive a permanent employment contract with pay in line with the IG-Metall collective agreement, including vacation and Christmas bonuses Work-life balance: 30 days' annual leave and a flexible working time account gives you plenty of freedom Strong company culture : Y ou can expect flat hierarchies and an open working atmosphere characterized by real teamwork Security for the future: We provide you with additional security with a company pension scheme and supplementary health insurance (visual aid, dentures, daily sickness allowance) Further goodies: JobRad, corporate benefits and much more Maintain and enhance the existing REST API (C#/.NET) within an agile development team Implement and manage backend infrastructure, ensuring robust security and reliability Collaborate closely with developers to translate requirements into clean, scalable, and testable solutions Participate in regular team planning and technical discussions to drive project progress Manage and optimize relational database systems (MariaDB), including schema design and performance tuning Conduct code reviews, write automated tests, and champion best practices in software quality 3–5 years of professional experience in backend development with C# and .NET Strong SQL skills and hands-on experience administering and optimizing relational databases (MariaDB, Entity Framework Core) Proven track record building and evolving RESTful APIs Solid understanding of software engineering principles, clean code, and maintainable architecture Hands-on experience with Docker and CI/CD pipelines—ideally using GitLab Fluent with Git for version control Experience working in agile/Scrum teams and a collaborative mindset Self-motivated, structured, and quality-focused, with strong analytical and problem-solving skills Fluent in English; German skills are a plus but not We are look ing forward to recei ve your complete application documents including your CV and references. We, Johannes and Nora from Recruiting, will be happy to answer any questions you may have!