Senior Backend Engineer (f/m/x) – API & Platform

Intro

Hamburg Hybrid (2–3 days/week onsite) | 70.000 - 85.000 € p.a. (40 hrs / full time) | 30 Days Vacation | English B2 | German C1

Are you passionate about building the technical backbone of the energy transition? Join suena energy as Senior Backend Engineer (f/m/x) and become a founding member of our newly formed Platform team. You'll help design and build the API and integration layer that connects our trading, analytics, and optimization systems — and in doing so, directly shape how clean energy is managed across European power markets.

suena energy is a green tech startup specializing in algorithmic energy trading for battery storage systems and renewables.

Our vision: a world where clean energy is used reliably, economically, and intelligently. With our AI-based optimization and trading software, we maximize the revenues of operators of large-scale energy storage and renewable assets on short-term electricity and balancing markets - while simultaneously minimizing their risks.

We're a team of 50+ people, combining a warm, supportive culture with real startup drive. Following our successful Series A, we're now building a dedicated Platform team from scratch.

Quick Check: Is this your kind of engineering challenge?

• Tech Stack: Python (Django/FastAPI), PostgreSQL/TimescaleDB, Redis, Celery, Docker, AWS, GitLab CI/CD, Sentry, Grafana
• Your Focus: API design & architecture, backend integrations, data flows, system reliability and scalability
• Team: Small, newly formed platform squad — you'll work closely with the Platform Lead, with strong support from our CTO in the early phase
• Product: Real-time energy trading platform — high complexity, data-heavy, ML-integrated
• Who thrives here: Engineers who think in systems, take ownership, and are energized by building things that actually matter
• Must-haves: 5+ years backend experience, solid API & architecture background, Python, cloud deployment, German C1
• Dealbreakers: No API/architecture experience, pure CRUD background, no interest in complex distributed systems

Your mission

• Design and build scalable, reliable APIs and backend integrations that connect trading, analytics, data science, and forecasting systems
• Drive the architecture of suena's platform layer — from initial design decisions to production
• Own data flows and backend automations across the platform
• Collaborate closely with the Platform Lead, CTO, and cross-functional teams (trading, data science, modelling) to translate complex domain requirements into robust technical solutions
• Improve and extend existing systems while keeping a clear eye on reliability, security, and performance
• Contribute to technical standards, code reviews, and engineering practices as the team grows

Your profile

• 5+ years of backend engineering experience, with a strong focus on API design and system architecture
• Solid Python skills (Django and/or FastAPI); hands-on experience with PostgreSQL/TimescaleDB is a plus
• Experience with distributed/cloud-based architectures (AWS preferred), Docker, CI/CD, async workflows (Celery, Redis)
• You think beyond the ticket — you understand how systems connect and can make principled architecture decisions
• Security-minded: authentication, authorization, zero-downtime deployments are familiar territory
• Comfortable working across greenfield projects and legacy systems
• German C1 is required for this role — we work closely with German-speaking external API partners and system integrators, and clear, direct communication in German is essential for this
• English B2/C1 for internal collaboration
• Nice to have: Experience or genuine curiosity about energy markets, trading systems, or related domains (finance, IoT). The domain is complex — enthusiasm to learn it matters.

Why us?

• Shape the Future: Contribute to the energy transi