Data Scientist

When travelers are searching for a hotel, we want the obvious choice to be trivago! Our leading metasearch engine is super fast and constantly optimized - enabling millions of travelers to compare hotel prices from hundreds of booking sites and find great deals in just a few clicks. We use cutting-edge technology, real-time auction, and machine learning techniques with petabytes of data to create an experience - time and money saved! In the lively city of Düsseldorf, we seize opportunities to learn everyday, innovate, and make an enduring mark on the travel industry. At trivago you will find those who aren't afraid of change but rather embrace it, turning every challenge into a pathway for growth. Join trivago, work with a great team, and grow with us!

• Own components end-to-end — from problem framing through to production deployment and business impact.
• Build and improve query understanding — intent classification, named entity recognition, slot filling, and semantic interpretation across 35+ languages.
• Design retrieval systems — candidate generation, dense and hybrid retrieval, and the recall-versus-latency trade-off at query time.
• Develop ranking and personalisation models — from training data construction and debiasing through to A/B testing and conversion impact — using both short-term in-session signals and long-term user behaviour.
• Apply and fine-tune language models where they improve the system — result explanation, query rewriting, and agentic approaches for complex and underspecified queries — with clear judgment on latency, cost, and quality trade-offs.
• Design offline and online evaluation frameworks — relevance judgement pipelines, cold-start evaluation, and retrieval and ranking quality metrics.

• 5+ years building and shipping search, ranking, or recommendation systems in production — Master's or PhD preferred, or equivalent demonstrated expertise.
• Deep theoretical knowledge and hands-on experience in at least one of: Learning-to-Rank, retrieval and candidate generation, query understanding and NLP, two-tower architectures, or personalisation — and working knowledge of the others.
• Experience fine-tuning and distilling transformer models for production — building efficient solutions optimised for real-world scale and latency.
• Solid foundation in experimentation — A/B test design, bias awareness, guardrail metrics, and connecting offline quality to online business outcomes.
• Strong Python and SQL; hands-on with PyTorch or HuggingFace; familiarity with vector search infrastructure, cloud ML pipelines (Vertex AI, Airflow), and GCP.
• Clear communicator, entrepreneurial drive, collaborative mentor, and motivation to make progress in ambiguous problem spaces.
• Outcome-driven: you care about the business impact of your work, not only the sophistication of the model or methodology.
• Hands-on, outcome driven and analytically rigorous — you take ownership end to end, build with quality in mind, and bring academic or professional rigour into real production environments.
• A learning and performance mindset — you set ambitious goals, seek feedback, stay curious, and actively explore how AI tools can enhance your work.

• Experience in travel, e-commerce, or two-sided marketplace search.
• Familiarity with marketplace dynamics and how advertiser signals interact with relevance ranking.
• Multilingual retrieval experience.
• Published research in information retrieval, ranking, or NLP — SIGIR, RecSys, WWW, or KDD.