About Wallround Wallround is headquartered in Berlin, with additional locations in Hamburg, Frankfurt am Main, Munich, Friedrichshafen and NRW. Our mission: we turn energy-efficient retrofits for multi-family residential buildings into predictable, lucrative investment opportunities. When it comes to modernisations, the real estate market is often a black box of rough estimates and fragmented processes. We are changing that. Through our integrated platform and streamlined workflow, we transform 'brown assets' into future-proof, high-yield properties. About the Role Department: Prod & Tech Functional Home: AI Reports to: CPO Location: Berlin, office-first Seniority: Senior We are looking for AI Senior Software Engineers to design and build the technical foundation behind our AI-powered products. You will be part of the AI Functional Home while working primarily within cross-functional product squads. You will collaborate closely with the AI Lead Product Manager, Product Design, Full-Stack and Backend Engineers, and Automation Engineers. This role is ideal for an engineer who enjoys moving between AI experimentation and production software engineering - taking an idea from prototype to reliable, scalable customer-facing functionality. Key Responsibilities AI Engineering Design and implement production-grade AI features and services. Work with LLMs, multimodal models, embeddings, RAG, agents, and AI APIs. Design AI workflows that are reliable, observable, and maintainable. Evaluate models and AI approaches against product requirements. Develop strategies for accuracy, hallucination reduction, latency, and cost optimization. Product Development Work directly with the AI Product Manager to turn product requirements into technical solutions. Rapidly prototype new AI capabilities and validate technical feasibility. Take successful prototypes into production. Contribute to technical product decisions and architecture. AI Infrastructure & Quality Build evaluation frameworks and testing approaches for AI systems. Implement monitoring and observability for AI applications. Establish appropriate guardrails and fallback mechanisms. Monitor model performance, latency, availability, and cost. Help establish reusable AI infrastructure and engineering patterns. Cross-Functional Squad Execution Act as a senior technical contributor within the AI Product Squad. Collaborate with Product, Design, Backend, Full-Stack, and Automation specialists. Break complex AI initiatives into executable technical work. Mentor other engineers and raise engineering standards across the AI Team. Participate in architectural and technical decision-making. What We are Looking For 6+ years of professional software engineering experience. Significant experience building production software using TypeScript and/or Java Python. Hands-on experience building applications with LLMs or other modern AI technologies. Strong understanding of APIs, distributed systems, databases, and cloud infrastructure(AWS, GCP, or Azure). Experience taking AI prototypes into production. Strong software engineering fundamentals: testing, version control, code review, observability, and maintainability. Ability to operate autonomously in a fast-moving product environment. Experience with RAG architectures and vector databases. Experience building AI agents and tool-calling systems. Experience with model evaluation and AI observability. Experience with LangChain, LlamaIndex, or equivalent frameworks. Experience with multimodal AI. Experience building B2B SaaS products. Success in the First 6–12 Months Deliver production-grade AI capabilities. Establish reliable AI engineering and evaluation patterns. Improve the quality, reliability, and cost efficiency of AI features. Build reusable AI components that accelerate future squads. Mentor engineers and contribute to the technical direction of the AI Team. What You’ll Own AI Architecture → AI Engineering → Production AI Systems → Evaluation → Reliability → Technical Excellence Why Join Wallround? Impact: Shape the future of energy-efficient retrofits and make a real contribution to climate action. Growth: Be part of a fast-growing startup with huge market potential. Team & Culture: Work alongside a highly motivated, experienced team in Berlin (Kreuzberg). Enjoy a vibrant startup culture, regular team events, and a modern workplace. Innovation: Flat hierarchies and fast decision-making—your ideas matter from day one. Flexibility & Development: Competitive salary, flexible working hours, and tailored personal growth opportunities. Perks & Benefits: €150 monthly benefit budget—use it for public transit tickets, meal allowances, or lifestyle perks (e.g., Urban Sports Club membership or vendor vouchers).