Machine Learning Engineer (Personalization)

Join our Personalization team in Barcelona as a Senior Machine Learning Engineer. In this role, you will design and build systems that deliver highly relevant, personalized experiences across our digital products. You will work at the intersection of backend engineering, data, and applied AI, leveraging modern architectures and machine learning techniques. Your responsibilities will include building scalable indexing, retrieval, and ranking systems, developing and improving ML models, driving experimentation and A/B testing, and optimizing systems for performance and scalability. You will collaborate closely with product, data science, and engineering teams.

• Design and build systems that deliver highly relevant, personalized experiences across digital products, focusing on backend engineering, data, and applied AI.
• Develop and improve machine learning models across the personalization stack, from candidate generation to final ranking, using data-driven methods.
• Drive experimentation and A/B testing to measure impact and iterate on models and features, leveraging large language models to enhance content understanding.
• Degree in computer science, machine learning, statistics, or equivalent work experience
• Familiarity with SQL and NoSQL databases
• 3+ years of industry experience applying machine learning methods, with a strong focus on recommender systems, search, ranking, or personalization
• Strong proficiency in Python for production ML systems
• Experience with A/B testing and experimentation frameworks to measure model impact
• Familiarity with cloud platforms (AWS, GCP, or Azure) and containerized environments