Senior Data Scientist

Join a hands-on ML modeling role focused on designing, training, improving, and productionizing machine learning models powering advertising, ranking, and recommendation systems in a large-scale, data-intensive environment.

Hands-on experience with Neural Networks and Deep Learning is mandatory. Experience limited to LLMs, GenAI, MLOps, AI Engineering, or prompt engineering is not sufficient for this role.

What you'll do

• Design, train, refine, and evaluate ML scoring models, including models related to CTR, CVR, and RoAS.
• Develop model strategies combining user, product, and placement signals.
• Design solutions suitable for high-throughput and low-latency production environments.
• Work closely with Engineering and Business teams to translate business goals into measurable modeling outcomes and technical roadmaps.
• Take ownership of the full model development lifecycle — from problem framing and feature engineering to evaluation and production handoff.
• Ensure high standards of quality and production readiness across Data Science workstreams.
• Provide technical guidance and mentor other Data Scientists.
• Work with large-scale datasets and independently make technical decisions within your area of responsibility.

Requirements

• Extensive hands-on experience designing, training, and improving Deep Learning models for production use cases.
• Strong practical experience with Neural Networks.
• Proficiency with PyTorch or TensorFlow.
• Strong Python skills, including writing production-level, testable, and documented code.
• Advanced SQL skills and experience working with large-scale data.
• Practical knowledge of Pandas and NumPy.
• Experience with public cloud infrastructure, preferably GCP.
• Experience with ML-oriented cloud services such as Vertex AI and Vertex Pipelines.
• Understanding of CI/CD practices.
• Experience leading model development end-to-end, from problem definition and feature design through evaluation and production deployment.
• Ability to mentor other Data Scientists and contribute to improving modeling standards.
• Relevant academic background or extensive professional experience in a STEM field.
• Strong independence, ownership, and decision-making skills.
• Professional working proficiency in English and native-level Polish.

Nice to have

• Experience developing ML models for low-latency online applications.
• Background in advertising, marketing, ranking, recommendation systems, or personalization.
• Experience with CTR/CVR modeling or predicting business events such as clicks and conversions.
• Knowledge of traditional ML techniques, including Gradient Boosted Trees.
• Experience in technical leadership, mentoring, or coordinating model development across a broader team.
• Experience using AI-assisted coding tools to improve engineering productivity and code quality.
• Experience with Docker.

Technologies

Python, PyTorch, TensorFlow, SQL, BigQuery, GCP, Vertex AI, Vertex Pipelines, Docker, Deep Learning, Neural Networks, Experiment Design, Low-Latency Model Development

Why join?

• Work on large-scale ML problems with real business impact.
• Build and improve production-grade models rather than working solely on exploratory analysis.
• Collaborate closely with experienced Engineering, Data Science, and Business teams.
• Have significant ownership over modeling decisions and technical solutions.
• Work on challenging problems involving advertising, ranking, and recommendation systems.
• Long-term collaboration in a remote-friendly environment.