Machine Learning Engineer

Senior Machine Learning Engineer — AdTech & Recommendation Systems
What's On Offer

• Competitive salary, depending on experience and seniority
• Hybrid working model based in Hamburg, Germany, with relocation and visa support available
• International, English-speaking environment
• Genuine technical ownership on large-scale deep learning, recommendation, and real-time serving systems
• Strong opportunities for career growth within a fast-moving Data Science organization

The Role We are supporting a leading mobile advertising platform, operating at massive scale across hundreds of millions of users, in growing their Machine Learning Engineering team. You'll be working on real-time bidding optimization, ad ranking, and conversion modeling — systems that make live decisions in milliseconds at massive scale.

• Build and optimize deep learning models for recommendation, ranking, and bidding
• Design and deploy real-time, low-latency inference systems serving live production traffic
• Develop scalable machine learning solutions using modern deep learning techniques
• Work with massive production datasets to improve model performance and business outcomes
• Own models end-to-end — from research and experimentation through production deployment and A/B testing
• Collaborate closely with engineering and product teams to translate ML into measurable business impact

What We're Looking For

• 5+ years of experience in Data Science, Machine Learning Engineering, or Applied Science
• Strong hands-on experience with deep learning frameworks (PyTorch and/or TensorFlow)
• Experience with large-scale recommendation systems, ranking, or personalization models
• Experience building and deploying real-time, low-latency production ML systems (online inference, live serving) — this is essential
• Strong Python and SQL skills, with experience integrating models into production pipelines
• Experience in AdTech, mobile gaming, e-commerce, or a similarly large-scale consumer platform
• Experience with real-time bidding or programmatic advertising is a strong plus

This role is focused on recommendation, ranking, and bidding systems — not conversational AI, RAG, or LLM application engineering. If your recent work has been primarily LLM/GenAI/chatbot development without a strong recommendation systems foundation, this likely isn't the right fit.
ApplyIf you're passionate about building large-scale, real-time machine learning systems in a fast-paced, high-impact environment, we'd love to hear from you. Apply today or get in touch for a confidential discussion.