Senior Fullstack Engineer & Hands-on Architect (Python / FastAPI) (m/f/d) in Köln

DEUTZ AG has evolved in recent years into a system provider of innovative and sustainable mobility and energy solutions. With around 6,000 employees worldwide and a global network of over 1,250 sales and service locations in more than 180 countries, we are actively shaping the transformation of mobility and energy supply. We continuously advance our technologies with a clear focus on market requirements, technological innovation, and social responsibility.

We are building a suite of digital products in the circular economy and remanufacturing space — the lifecycle of engines and components, the processes around reconditioning, and the connected service and partner network. This is a product role, not a ticket role: you work directly with domain experts, shape what gets built and how, own the architecture of the services behind it, and take features from idea to production. Backend is the center of gravity; fullstack experience is required to work with the frontend team and judge end-to-end feasibility. We work agentic: AI coding agents are part of the daily toolchain. We expect you to use them to move fast and to review and steer their output with the same rigor you would apply to any production code. Language: German is the primary project language, English fluent (business-level).

Responsibilities:

• Own the technical architecture: domain boundaries, data models, service cuts, integration patterns, ADRs
• Design and implement backend-heavy features and APIs in FastAPI — lifecycle and process data, matching and marketplace-style flows, partner and logistics integration
• Shape the product with domain experts: challenge requirements, propose simpler solutions, define MVP scope and what comes after
• Design resilient, well-documented interfaces to surrounding systems and external partners
• Raise delivery speed through modular architecture, reusable components and effective use of coding agents
• Strengthen quality practices (unit/integration testing, linting, formatting, review standards)
• Work with QA, product and platform teams on smooth release cycles; support CI/CD and deployment readiness from a developer perspective (no primary DevOps ownership)

Must-Haves:

• Several years of production software development
• Strong backend expertise in Python and FastAPI
• Hands-on architect for product-facing services — not architecture on slides
• Hands-on frontend experience to understand UI integration constraints
• Complex business logic in clean, testable, maintainable code
• Data-centric products: domain entities, lifecycle/state handling, traceability across process steps
• Practical experience working with AI coding agents and the judgment to review their output critically
• Microservice collaboration patterns and integration concerns
• Works directly with business stakeholders and turns vague domain input into a buildable increment

What we offer:

• Full-time
• 30 days of vacation per year
• Option to work remotely
• Extensive range of training and professional development opportunities
• Employee benefits from various providers, both online and in-store
• Comprehensive healthcare provision (e.g. flu and COVID-19 vaccinations, carotid artery screening) with our own in-house medical centre
• Staff canteen and kiosk on the worksite
• Good public transport links, as well as free parking
• Discounted Urban Sports Club membership

Are you looking for a varied and exciting role in a supportive team, with attractive remuneration and ideal working conditions? If so, we look forward to getting to know you!

We welcome and support the diversity of our workforce and are convinced that it is one of the most important factors in our company’s success. Diversity makes us more open-minded, innovative and competitive.

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