Senior Data Scientist

Stack

Responsibilities

• ▹Design, refine and evaluate ML scoring models (e.g. CTR, CVR, RoAS) that are integral to core bidding logic
• ▹Architect model strategies that combine user, product and placement signals, ready 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 to ensure alignment with production standards

Requirements

• ▹Extensive hands-on experience designing, training and improving Deep Learning models for business-critical production use cases
• ▹Proven expertise in PyTorch or TensorFlow, plus strong practical knowledge of Pandas and NumPy
• ▹Advanced SQL skills, preferably analytical SQL used in large-scale data environments
• ▹Strong experience with public cloud infrastructure, preferably Google Cloud Platform, including Vertex AI and Vertex Pipelines
• ▹Ability to lead end-to-end model development, from problem framing and feature design to evaluation and production handoff
• ▹Production-level, testable, documented Python code and 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, Physics)
• ▹English level min. B2

Nice to have

• ▹Experience developing ML models for low-latency online applications
• ▹Experience in the advertising or marketing domains
• ▹Experience developing ML models for predicting clicks or conversions (CTR and 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

Soft skills

What we offer

• ▹25–30k PLN on a B2B contract
• ▹Access to the Worksmile platform
• ▹A work environment that values growth and innovation

About the company

The Codest is an international tech software company with tech hubs in Poland, focused on web development, cloud engineering, DevOps and quality. Its own product, Yieldbird, was a Deloitte Top25 laureate; today it helps tech companies build products and scale IT teams. The project client is one of the largest e-commerce platforms in Europe.