Your Mission As Lead Fullstack Engineer at hallo theo, you design, build and operate the core systems of our AI-native property management platform. You work hands-on across the stack - from intuitive frontends to robust backend services and data flows - and take real ownership for critical user journeys. Build and evolve reliable backend and frontend components (APIs, services, UIs) that integrate with our web tech stack and data layer. Act as a technical sparring partner and mentor for other engineers, supporting good engineering practices and a healthy engineering culture. Preferred Background 6-8 years of experience in software engineering, ideally in product-driven environments (startups, scale-ups or similar), with a strong track record in complex and uncertain projects. Proficient in at least one modern programming language and experienced in a web tech stack (e.g. Python and SQL, plus modern web frameworks and APIs). Business-fluent German (C1 or higher) and strong English skills, as you’ll work with German-speaking stakeholders and an international team. Nice to have Experience in domains with complex operations or workflows (e.g. proptech, fintech, marketplaces or B2B SaaS). Prior experience in a "tech lead” capacity (leading projects or streams), even without formal line management. With a clear, ambitious vision and a tech- and AI-first operating model, you’ll have the autonomy and responsibility to shape our platform, our engineering practices and the future of property management in Germany.