Machine Learning Scientist I - Performance Marketing in Manchester

About Us
Booking.com, data drives our decisions. Technology is at our core. And innovation is everywhere. But our company is more than datasets, lines of code or A/B tests. We’re the thrill of the first night in a new place. The excitement of the next morning. The friends you encounter. The journeys you take. The sights you see. And the memories you make. Through our products, partners and people, we make it easier for everyone to experience the world.

About the team
The PPC team builds and optimizes large‑scale ML models for online bidding across all major search providers, owning one of the industry’s largest performance and auction strategies to keep Booking.com competitive. We run end‑to‑end research‑to‑production cycles—from POCs and modeling to large‑scale A/B testing—driving measurable impact by optimizing auction levers at scale.

Role description
As a Machine Learning Scientist in PPC, your work will focus on devising and implementing advanced machine learning and optimization approaches for the next generation of Booking.com performance marketing bidding algorithms. Specifically, you will work on optimizing our bidding strategy across search platforms, ensuring our competitive edge in the complex dynamics of the bidding marketplace and online auction mechanisms. This role requires a unique combination of deep theoretical knowledge around large-scale optimization techniques, auction theory and applying state of the art machine learning methodologies to scalable industrial setups.

Responsibilities

• Develop innovative techniques for the next phase of our online bidding algorithms, including modeling user intent, modeling the online marketplaces, and optimizing our bidding strategy to maximize the efficiency of how we spend our advertising budgets.
• Design and implement scalable evaluation pipelines, including synthetic data generation and benchmarking for model quality, relevance, and consistency.
• Ensure the reliability, efficiency, and scalability of evaluation tools and frameworks in both offline and online environments.
• Conduct in-depth data analysis to define and track evaluation metrics, validate label quality, and explore performance across different traffic siloes.
• Collaborate closely with ML engineers to integrate evaluation components into production pipelines, supporting continuous improvement of bidding applications.
• Work cross-functionally with commercial and analytics teams to align evaluation strategies with business goals and user impact.

Role Qualifications And Requirements
Master’s degree or PhD required (Computer Science, Engineering, Mathematics, Artificial Intelligence, Physics).
Industry or academia knowledge of large scale optimisation techniques or mechanism design or auction theory.
Experience contributing to innovative machine learning and optimization solutions for large-scale business problems. Preferably evidenced by peer-reviewed publication, patents, open sourced code or the like.
Relevant work or academic experience (MSc + 1 year of working experience), involved in the application of Machine Learning to business problems.
Knowledge of some machine learning facets: working with large data sets, model development, statistics, experimentation, data visualization, optimization, software development.
Understanding of cross-functional development of machine learning products (e.g. Developers, Commercial, Data Analytics, etc.).
Working knowledge of Python, SQL/BigQuery, Spark.
Excellent English communication skills, both written and verbal.

Benefits & Perks
Booking.com’s Total Rewards Philosophy is not only about compensation but also about benefits. We offer a competitive compensation and benefits package, as well unique-to-Booking.com benefits which include:

• Annual paid time off and generous paid leave scheme including: parent, grandparent, bereavement, and care leave.
• Hybrid working including flexible working arrangements, and up to 20 days per year working from abroad (home country).
• Industry leading product discounts - up to 1400 per year - for yourself, including automatic Genius Level 3 status and Booking.com wallet credit.
• Contributing to a high scale, complex, world renowned product and seeing real-time impact of your work on millions of travelers worldwide.
• Working in a fast-paced and performance driven culture.
• Opportunity to utilize technical expertise, leadership capabilities and entrepreneurial spirit.
• Promote and drive impactful and innovative engineering solutions.
• Technical, behavioral and interpersonal competence advancement via on-the-job opportunities, experimental projects, hackathons, conferences and active community participation.
• Competitive compensation and benefits package.

Diversity, Equity and Inclusion (DEI)
Diversity, Equity & Inclusion have been a core part of our company culture since day one. This ongoing journey starts with our very own employees, who represent over 140 nationalities and a wide range of ethnic and social backgrounds, genders and sexual orientations. We ensure that colleagues with disabilities are provided the adjustments and tools they need to participate in the job application and interview process, to perform crucial job functions, and to receive other benefits and privileges of employment.

Application Process
Let’s go places together: How we Hire
This role does not come with relocation assistance. Booking.com is proud to be an equal opportunity workplace and is an affirmative action employer. All qualified applicants will receive consideration for employment without regard to race, color, religion, gender, gender identity or expression, sexual orientation, national origin, genetics, disability, age, or veteran status. We strive to move well beyond traditional equal opportunity and work to create an environment that allows everyone to thrive.