Senior Data Scientist

Quick Facts

• Role: Senior Data Scientist (remote; occasional meetings max once per quarter)
• Focus: hands-on ML modeling for advertising, ranking, and recommendation systems
• Language: Polish (native), English (min B2)

Description

Join as a Senior Data Scientist to design, train, refine, evaluate, and productionize machine learning models in a large-scale, data-intensive environment. This is a hands-on ML modeling role with independent end-to-end ownership of modeling problems, requiring strong Deep Learning and Neural Networks experience. Hands-on experience with Neural Networks and Deep Learning is mandatory; experience limited to LLMs/GenAI/MLOps/AI Engineering/prompt engineering is not sufficient.

Responsibilities

• 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 with Engineering and Business teams to translate business goals into measurable modeling outcomes and technical roadmaps
• Take ownership of the full model development lifecycle: problem framing, feature engineering, evaluation, and production handoff
• Ensure quality and production readiness across Data Science workstreams
• Provide technical guidance and mentor other Data Scientists
• Work with large-scale datasets and make independent technical decisions within your area

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 (problem definition, feature design, evaluation, and production deployment)
• Ability to mentor other Data Scientists and improve 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

Benefits

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