Lead Data Scientist (Ads)

Location: Berlin, Germany. Hybrid work with 2 recommended office days per week; remote work is available under a workation policy for up to 90 days per year in the EU, including 21 days globally, and for non-EU citizens, 21 days worldwide.

Annual gross salary: €90,100–€132,500 EUR.

Company

A European second-hand marketplace connecting millions of members across more than 20 markets, with additional shipping and payment business units.

What you will do

• Own the data science approach for Ads optimization problems including ranking, targeting, pacing, budget allocation, candidate selection, auctions, and bidding.
• Design, develop, and iterate prediction, scoring, calibration, exploration/exploitation, and constrained optimization models for Ads delivery.
• Lead experimentation and performance improvement frameworks, defining hypotheses, evaluation methods, metrics, and guardrails.
• Design objectives and constraints balancing advertiser value, revenue, user experience, and operational requirements.
• Diagnose delivery, relevance, auction, supply-demand, and model performance issues and propose improvements.
• Partner with Product Managers, Decision Scientists, Analytics Engineers, Data Engineers, backend developers, and other Data Scientists to implement reliable production systems and explain performance drivers to non-technical stakeholders.

Requirements

• Strong applied machine learning and statistical skills.
• Experience with Ad Tech systems and optimization problems, such as ads ranking, auction systems, pacing and budget optimization, marketplace or recommendation systems, relevance modeling, or other real-time optimization environments with multiple objectives.
• Strong product and business judgment, with the ability to work effectively in ambiguous and evolving domains.
• Comfort working on production systems with engineers.
• Well-versed in Python and SQL.
• Structured and meticulous approach to testing different approaches toward a defined goal.
• Collaborative working style, with proactive alignment when work affects other team members.
• Ability to explain machine learning methods to non-technical audiences.
• Solid written and spoken English.

Nice to have

• Experience with BigQuery.

Culture & Benefits

• Hybrid work model with flexibility to work from home and collaborate in the office.
• 30 days of paid annual leave, supplemental private health insurance, life and disability insurance, and a pension plan with a 150% employer match on the chosen contribution.
• Share options, learning budget starting at €3,000 per year, and up to 10 paid learning days over two years.
• Home office equipment and a budget of up to €540 for furniture, plus a lunch benefit and subsidised Deutschlandticket.
• Digital mental and emotional health support, Employee Assistance Program, discounted gym membership, and a personal monthly shopping budget.
• Dog-friendly office and frequent team-building events.