Senior Data Scientist, Personalization & Contextual RL

Joinimagine; Województwo mazowieckie; On-site; PLN 300,000 - 420,000; Full time

Benefits offered by this job

Workspace at Warsaw Centre Point

Job summary

HelloFresh in Warsaw, within HelloTech, builds the digital backbone powering our end-to-end food experience. As a Senior Data Scientist, you will drive AI-enabled communications, personalization, and content search across global markets, shaping data-driven products with a modern tech stack and international teams.

You will own RL/ML models, design decisioning, and collaborate cross-functionally to deliver scalable, high-impact solutions while ensuring safety, latency, and data reliability in

Qualifications

• 5+ years of professional experience in data science or ML with production deployments.
• Proficiency in Python and modern ML stack (Databricks/Spark, MLflow).
• Direct experience with reinforcement learning and contextual bandits (e.g. Thompson Sampling).
• Strong experimentation and causal inference foundations for high-traffic settings.

Responsibilities

• Build, own, and iterate on RL/ML models in production for high-traffic conversion and communication flows.
• Develop decisioning logic for best actions across funnel and messaging lifecycle.
• Advance contextual-bandit system architecture toward offline policy evaluation and low-latency inference.
• Collaborate with Engineering to integrate models into funnel and messaging architecture with robust fail-safes.

Skills

Python

Databricks

Spark

MLflow

Reinforcement learning

Contextual bandits

Experimentation

Causal inference

Production ML

Communication

Tools

Databricks

Spark

MLflow

Job description

HelloFresh in Warsaw, within HelloTech, builds the digital backbone powering our end-to-end food experience. As a Senior Data Scientist, you will drive AI-enabled communications, personalization, and content search across global markets, shaping data-driven products with a modern tech stack and international teams.

You will own RL/ML models, design decisioning, and collaborate cross-functionally to deliver scalable, high-impact solutions while ensuring safety, latency, and data reliability in