Senior Software Developer (m/f/d) Java/Kotlin with Spring Boot

Do you want to build software that truly makes an impact? At etalytics, we develop intelligent energy management solutions that help industrial companies reduce energy consumption, lower CO₂ emissions, and cut costs. With our AI- and data-driven products, we actively contribute to a more sustainable future. As a Senior Software Developer, you will join our backend team in Darmstadt and work on our etaONE® platform. You will take technical ownership, actively contribute to architectural decisions, and support the growth of our engineering team with your experience. If you care about clean code, modern architectures, and meaningful software, you will feel right at home with us. Tasks: Design, develop, and maintain scalable backend features – from REST APIs to the persistence layer – using Spring Boot with Java and/or Kotlin Actively contribute to the evolution of our cloud-native microservice architecture Continuously improve our system landscape using modern technologies such as Docker, Kubernetes, CI/CD pipelines, and asynchronous pub/sub mechanisms Provide technical and functional input for new product and solution ideas, including architecture and technology decisions Ensure high code quality and long-term maintainability through test-driven development, automated testing (e.g., JUnit, Mockito, MockK), and static code analysis Mentor and support junior developers while fostering a strong engineering culture focused on learning and knowledge sharing Collaborate closely with product management, developers, and domain experts to translate business requirements into scalable technical solutions Actively participate in internal knowledge exchange and continuously stay up to date with backend, cloud, and software engineering trends Must-have: At least 5 years of professional experience in backend software development with Spring Boot or comparable frameworks Strong proficiency in Java and/or Kotlin Experience in building RESTful APIs as well as working with SQL and data modeling Hands-on experience with relational databases, ideally PostgreSQL Solid understanding of software architecture, clean code principles, and modern software engineering practices Experience with CI/CD pipelines and automated testing (e.g., JUnit, Mockito, MockK) Experience in taking technical ownership, mentoring, or supporting less experienced developers Fluent English skills, both written and spoken Nice-to-have: Hands-on experience with Docker and container-based architectures Experience with Kubernetes and cloud-native platforms Experience with asynchronous architectures or event-driven systems German language skills are a plus Benefits: Purpose-driven work: Support industrial companies in becoming more efficient and sustainable Flexibility: Hybrid working with home office options and flexible working hours Team spirit: A supportive, collaborative environment with plenty of room for exchange and cooperation Community: Regular team events and shared activities Work-life balance: 30 days of vacation plus a flexible, agile work culture Well-being: Tax-free benefits card, subsidized local gym membership and the option of a job bike