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Senior Fullstack AI Engineer (w/m/d)

Stackfuel • Berlin
100% English First
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Job description

For years, StackFuel has been one of Germany’s leading providers of data and AI training. Since early 2026, we have been part of Multiverse, Europe’s only EdTech unicorn and the continent’s largest AI upskilling platform. Together, we are pursuing a clear goal: to make 100,000 employees in Germany AI-ready and close the country’s data and AI skills gap.

To make this happen, we are building a next-generation adaptive learning platform from Berlin, AI-first from the ground up. Alongside this, we develop software tools and automations that integrate into our customers’ B2B platforms. As a Senior Fullstack AI Engineer (m/f/d), you’ll play a key role in shaping this platform and these software tools, from the database to the frontend. Your work directly reaches thousands of learners and contributes to the transformation of mid-sized and large German companies.

Your responsibilities

  • Develop our adaptive, AI-first learning platform and software-based AI solutions end-to-end, independently making key technical architecture decisions

  • Implement new features and requirements in our existing learning framework, balancing new development with ongoing improvements

  • Build AI features into the platform, such as LLM-powered learning support, adaptive learning paths, or automated content generation, and ensure they run reliably, measurably, and cost-efficiently

  • Build internal tools and AI automations for Learning Coaches, Client Operations, and Sales to help these teams work more efficiently

  • Work closely with the entire engineering team, our Content Engineering team, and the Portfolio Leads

What you bring

  • 5+ years of experience in full-stack development, several of them with senior responsibility (architecture, technical decisions, mentoring)

  • You work AI-first and naturally use AI tools in your day-to-day engineering; the agentic SDLC isn’t a foreign concept to you but a target vision

  • Hands-on experience with LLM APIs in products: prompt design, structured outputs, tool use, and evaluation of model outputs

  • Experience with end-to-end development using Python (FastAPI or Django) and TypeScript/React

  • Confident with PostgreSQL and schema migrations

  • Discipline in testing and CI (e.g.…