Senior Software Engineer (Backend)

This is us Lumenaza is a green-tech company building software for the decentralized energy world. Our platform enables energy providers to manage billing, market communication, and energy data — supporting renewable energy business models at scale. We are driven by a clear mission: accelerating the transition to a sustainable energy system. At the same time, we value diversity, collaboration, and continuous learning. Your tasks Your Role As a Senior Backend Engineer, you will design and build core systems that power real-world energy processes — from billing to market communication. You take ownership of complex domains, contribute to architectural decisions, and help evolve both our systems and engineering practices. What You’ll Do Build and own core backend systems Design and implement scalable solutions for billing, tariff models, and energy market processes. Shape system architecture Work across the full lifecycle — from design to deployment — ensuring maintainability, scalability, and correctness. Solve complex technical challenges Develop robust solutions involving data modeling, asynchronous processing, and distributed systems. Collaborate across disciplines Work closely with Product, Frontend, and DevOps to deliver cloud-based solutions and improve our platform. Drive improvement and innovation Bring in new ideas, improve engineering practices, and explore modern development approaches, including AI-assisted workflows. Modernize existing systems Help evolve and migrate legacy systems toward modern architectures. Your profile Core Requirements 5+ years of backend development experience Strong Python and Django expertise Experience designing and building REST APIs Experience with distributed systems / microservices Solid understanding of databases (PostgreSQL) Experience with Docker and CI/CD workflows Strong communication skills in English Nice to Have Experience with FastAPI, Pydantic, or Django Ninja Knowledge of Celery or similar async tools Experience integrating external systems (e.g. ERP, APIs) Familiarity with React / TypeScript Interest in energy markets or regulated domains Our Tech Stack Python, Django, Django REST Framework PostgreSQL, Redis Celery (async processing) Docker, Kubernetes GitLab CI/CD Robot Framework (testing) React (frontend) We deploy continuously to Kubernetes and work with distributed systems handling complex, business-critical data. We offer you this Impact: Build software that directly enables renewable energy business models Ownership: Work on complex, meaningful systems with real-world impact Growth: Structured onboarding and continuous learning Flexibility: Flexible hours and hybrid work setup Benefits: Competitive compensation, Deutschlandticket Location: Modern office in Berlin Kreuzberg We strongly encourage applications from underrepresented groups in tech and are committed to building an inclusive environment. About Us Lumenaza GmbH, through its brand Lumenaza.Community, is a leading provider of direct marketing for small-scale installations and a supplier of electricity for household tariffs ranging from fixed to dynamic contracts. The Lumenaza Community represents green, decentralized electricity generation. Since 2013, Lumenaza GmbH has also been supporting major energy supply companies such as EnBW and E.ON as a software and service provider, offering innovative solutions in billing, market communication, and virtual power plants. For more information, visit Lumenaza.Community and www.lumenaza.com.