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Senior Data Scientist, Growth Alliance

Warszawa, Masovian Voivodeship, Poland💼 Full-time🗓 2026-07-30 → 2026-09-26

Core

Designing and scaling AI agents using contextual bandits to optimize communication channels (email, SMS, push) and personalize post-click landing page journeys for HelloFresh customers.

Role type

Senior IC machine-learning engineer (contextual bandits, reinforcement learning)

Builds

Production decisioning systems for user communication and funnel optimization

Domain

Direct-to-consumer food subscription, personalization, marketing technology

Deliverable

production ML models

Required skills

Python, reinforcement learning, contextual bandits, experimentation design, causal inference, classical machine learning, customer behavior data analysis

Preferred skills

off-policy evaluation, propensity methods, sequential testing (SPRT), streaming/low-latency inference, unstructured data embeddings

Technologies

Databricks, Spark, MLflow, Thompson Sampling, Counterfactual Risk Minimization, Offset Trees

Responsibilities

Build and iterate RL/ML models for high-traffic conversion flows; Develop decisioning logic for user actions across the messaging lifecycle; Drive architectural evolution of contextual-bandit systems; Partner with Engineering on system design and latency handling; Own experimentation design and metric definition; Monitor model performance, data drift, and latency in production

Seniority

Senior, hands-on IC

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