We bring startups and disruptive tech companies to the local market, offering engineers the opportunity to work on innovative, high-impact products. Join us and become a member of their R&D team while we take care of employment, HR support, a benefits package, and an enjoyable work environment.We’re looking for ML Researcher to join the team at a performance-marketing agency that works across more than 25 industry verticals. They focus on using advanced data analytics and tailored creative strategies to drive conversions — the agency handles everything from lead generation and campaign optimisation (through search, social media and newer platforms) so their clients can focus on growth. Responsibilities Develop, train, and evaluate ML models, with a focus on tabular, predictive, and ranking models Contribute to production-ready modeling pipelines, ensuring models are robust, scalable, and optimized for deployment Perform data wrangling, feature engineering, and dataset preparation for modeling at scale Translate hypotheses into measurable experiments and actionable insights Collaborate with cross-functional teams to integrate ML models into production systems Continuously monitor, optimize, and refine models for accuracy, efficiency, and business impact Requirements Strong hands-on experience with tabular ML models (XGBoost, LightGBM, CatBoost, logistic regression, etc.) Proven experience with data wrangling, feature engineering, dataset preparation Experience training, tuning, and evaluating models at scale Solid understanding of model validation Strong Python skills and familiarity with ML libraries Ability to translate hypotheses into measurable experiments Experience working closely with data engineering pipelines Nice to Have Experience with inference engineering: packaging models, building inference endpoints, optimizing latency Exposure to model monitoring: drift, data quality checks, performance monitoring Experience with containerization (Docker) and serving frameworks (FastAPI, Flask, TorchServe, Bento, etc.) Experience deploying ML models in production environments Prior experience with ranking, scoring or optimization models Benefits Work in a highly professional team. Informal and friendly atmosphere in the team Paid vacation — 20 business days per year, 100% sick leave payment Equipment provision Partially compensated educational costs (for courses, certifications, professional events, etc.) Legal and Accounting support in Poland Ability to work from our comfortable downtown office in Warsaw 5 sick days per year Medical insurance (after the end of the probationary period) English and Polish classes 2 times a week (online) Bright and memorable corporate life: corporate parties, gifts to employees on significant dates