Senior Data Scientist

🌍 Hello World! We are The Codest - International Tech Software Company with tech hubs in Poland delivering global IT solutions and projects. Our core values lie in “Customers and People First” approach that prioritises the needs of our customers and a collaborative environment for our employees, enabling us to deliver exceptional products and services. Our expertise centers on web development, cloud engineering, DevOps and quality. After many years of developing our own product - Yieldbird, which was honored as a laureate of the prestigious Top25 Deloitte awards, we arrived at our mission: to help tech companies build impactful product and scale their IT teams through boosting IT delivery performance. Through our extensive experience with product development challenges, we have become experts in building digital products and scaling IT teams. But our journey does not end here - we want to continue our growth. If you’re goal-driven and looking for new opportunities, join our team! What awaits you is an enriching and collaborative environment that fosters your growth at every step. Project description: Our client is one of the largest e-commerce platforms in Europe, used by millions of users every day. The company connects sellers - from small businesses to global brands - with customers, offering a vast product selection, fast delivery, and a well-crafted shopping experience. The role: Senior Data Scientist specializing in ML Models for Advertising and Ranking Domains. Drive the design, refinement, and evaluation of ML scoring models (e.g., CTR, CVR, and RoAS), integral to core bidding logic. Architect model strategies for complex solutions integrating user, product, and placement signals, ensuring readiness for high-throughput and low-latency environments. Partner with engineering and business stakeholders to translate strategic goals into measurable modeling outcomes and technical roadmaps. Provide technical leadership and quality assurance for Data Science workstreams within the project scope to ensure alignment with production standards. Specific skills and tools Python, PyTorch, TensorFlow, SQL (BigQuery), Docker, GCP, Vertex AI, Vertex Pipelines, Deep Learning, Experiment Design, and Low-Latency Model Development. Extensive hands-on experience in designing, training, and improving Deep Learning models for business-critical production use cases. Proven expertise in deep learning frameworks such as PyTorch or TensorFlow, as well as strong practical knowledge of Pandas and NumPy. Advanced SQL skills, preferably including analytical SQL used in large-scale data environments. Strong experience with public cloud infrastructure, preferably Google Cloud Platform, including ML- oriented services such as Vertex AI and Vertex Pipelines. Proven ability to lead end-to-end model development, from problem framing and feature design to evaluation and production handoff. Strong engineering foundations, including writing production-level, testable, and documented Python code, with familiarity with CI/CD practices. Ability to mentor other Data Scientists and raise modeling standards across the team. Relevant academic degree or extensive professional experience in a STEM field (e.g. Computer Science, Mathematics, Mathematical Statistics, Quantitative Methods, or Physics). English level min. B2. Nice to have: Experience in developing ML models for low-latency online applications. Experience within the advertising or marketing domains. Demonstrated experience in developing ML models for predicting business events like clicks or conversions (i.e., Click-Through Rate (CTR) and Conversion Rate (CVR) modelling). Proficiency in traditional machine learning techniques, such as Gradient Boosted Trees. Experience in mentoring, technical leadership, or coordinating model development across a broader team. Practical use of AI-assisted coding tools to improve engineering productivity and quality. Our offer: 25–30k PLN on a B2B contract Access to the Worksmile platform A work environment that values growth and innovation - you bring the ideas, and we want to hear them 😉 Recruitment process: 30-minute screen with our recruiter, Justyna Profile screening by Manager Client Technical Verification Meetings Stakeholder meeting Offer Questions, insights? Feel free to reach out to our recruiting team: In the meantime, feel free to visit our website where you can find key facts about us.