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GRAI

Senior Machine Learning Engineer (RecSys)

GRAI
Warsaw, Poland1 months ago
R&DSeniorFull-timeRemote
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About this role

We are building an AI-powered music platform that’s transforming how people create, explore, and experience music. Our product leverages cutting-edge AI technologies to provide personalized music recommendations and unique features tailored to every music enthusiast.

As we continue to grow, we’re looking for a Senior Machine Learning Engineer to design, build, and scale recommendation systems that deliver highly relevant, personalized experiences to our users. You will work on large-scale user interaction data, develop retrieval and ranking models, and take them from experimentation to production.

What You’ll Do

  • Design and implement retrieval and ranking architectures for personalized recommendations

  • Work with large-scale user behavior and content data to extract meaningful signals

  • Build end-to-end ML systems: data processing, feature engineering, training, evaluation, deployment, monitoring

  • Run A/B tests and offline evaluations to measure model impact and guide improvements

  • Collaborate with product and engineering teams to align recommendations with business goals

  • Continuously monitor model performance

What We’re Looking For

  • Strong hands-on experience building recommendation systems or ranking models

  • Deep understanding of machine learning fundamentals and evaluation methodologies

  • Experience working with large-scale data (SQL, Spark, or distributed data systems)

  • Proficiency in Python and modern ML frameworks (PyTorch, TensorFlow)

  • Understanding of core ML concepts: supervised/unsupervised learning, evaluation metrics, feature engineering

  • Experience deploying ML models to production and maintaining them over time

  • Ability to balance experimentation with production reliability

Nice to Have

  • Experience with real-time recommendation systems

  • Knowledge of search / information retrieval systems

  • Familiarity with feature stores, model monitoring, and ML infrastructure

  • Experience in media, music, or consumer-facing personalization products

Why Join Us

  • Work on high-impact ML systems used by real users at scale

  • Ownership over meaningful technical decisions, from modeling to production

  • Collaborative, product-driven environment with strong engineering culture

  • A supportive and dynamic startup culture where your ideas and contributions truly matter

  • Opportunities for growth, learning, and shaping the future of our recommendation stack