Senior ML Software Engineer - Growth & Lifecycle / Lounge by Zalando (all genders)

Role: Senior ML Software Engineer – Growth & Lifecycle team at Lounge by Zalando. You will own and grow machine‑learning systems that personalise campaign ordering across multiple channels. Responsibilities: - Own personalisation end‑to‑end, extending the campaign‑ordering ranking system to email and other channels. - Design and implement feature engineering pipelines in Spark/Databricks, maintain a feature store and ensure pipeline parity. - Build and operate scalable batch (and where applicable real‑time) inference serving millions of requests. - Develop tracking, attribution and A/B testing to measure lift and impact. - Integrate data‑science models (churn, next‑best‑action, propensity) into lifecycle messaging. - Lead production‑readiness reviews, define technical standards and mentor mid‑level and junior engineers. Qualifications: - Proven experience productionising machine‑learning models, including feature pipelines, training workflows and model serving. - Strong big‑data skills with Spark (preferably on Databricks) and feature‑engineering for recommendation/ranking systems. - Deep expertise in production‑grade Python for ML; familiarity with Kotlin is a plus. - Experience with cloud‑native ML ops on AWS (SageMaker or similar), Kubernetes, CI/CD and observability. - Ability to design rigorous experiments, A/B tests and evaluate models both offline and online. - Comfortable using AI coding tools and agent‑assisted workflows. - Excellent communication and senior‑level collaboration skills. What We Offer: - Employee shares program. - 40% discount on Zalando fashion and beauty products, 30% on Lounge. - Two paid volunteering days per year. - 27 days of vacation (starting amount). - Relocation assistance (subject to agreement). - Family services, health and wellbeing options, mental health support and coaching. - Continuous development through training platform and peer‑to‑peer reviews.