About Us: At 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 Senior Machine Learning Engineer in  PPC, you will design, build and maintain production‑grade ML systems that directly impact how we invest our marketing budget and set bids across all major search partners at scale.

You will work across the  ML lifecycle: understanding business problems with stakeholders, shaping data requirements, building and operating the data foundations, building robust feature pipelines on top of our data and ML platforms, and running and monitoring experiments in production .You will collaborate closely with  ML scientists,  engineers and specialists to develop the next generation of Booking.com performance marketing bidding algorithms. This is a hands‑on engineering role with clear and measurable business impact.

Key Job Responsibilities and Duties:

• Develop production-grade AI systems, from models to features and pipelines, accounting for reliability, scalability, real-time requirements, monitoring and retraining.

• Build readable and reusable code, applying code quality best practices and using standard libraries.

• Choose the right technology or coding methodology as well as refactor and simplify code when necessary.

• Take full ownership of your services end to end by actively monitoring the systems health, performance and business impact.

• Be responsible for business related data governance processes, the technical implementation and maintenance of data processing services and storage systems, and the implementation and maintenance of AI governance processes.

• Evaluate possible architecture solutions taking into account the business and technology requirements.

• Set the relevant service level objectives SLOs and act accordingly when they are not met.

• Build readable and reusable code, using the right technologies and coding methodologies applying knowledge of business area tools and product needs.

• Continuously evolve your craft by keeping up to date with the latest developments in ML/AI and related technologies and upskilling on these, as needed. 

• Contribute to the internal ML/AI community by sharing your knowledge and participating in our internal AI programs

• Coach others through evidence and clear communication, explaining advanced technical concepts in simpler terms.

• Maintain a highly cross-disciplinary perspective, solving issues by applying approaches and methods from across a variety of disciplines and related fields.

• Achieve mutually agreeable solutions by staying adaptable, communicating ideas in clear coherent language and practising active listening.

Role Qualifications and Requirements:

• 5+ years of relevant work experience (or equivalent), involved with the application of Machine Learning to business problems in a commercial environment.

• Advanced knowledge and experience in areas like e.g. GenAI, Agentic Systems, Recommender Systems, Deep Learning, Information Retrieval, Computer Vision, Speech Recognition, Causal Inference, MLOps, etc

• Work experience (or equivalent), involved with the application of ML/AI to business problems in a commercial environment.

• Demonstrable experience of multiple machine learning facets, such as working with large data sets, experimentation, evaluation, scalability and optimization.

• Experience with data-driven product development: analytics, A/B testing, etc.

• Strong experience in one or more general purpose programming languages.

• Working experience with version control systems.

• Excellent English communication skills, both written and verbal.

Benefits & Perks - Global Impact, Personal Relevance:

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 

• Living and working in Amsterdam, one of the most cosmopolitan cities in Europe

• 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 and some great added perks of working in the home city of Booking.com

Diversity, Equity and Inclusion (DEI) at Booking.com: 

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. 

Take it from our Chief People Officer, Paulo Pisano: “At Booking.com, the diversity of our people doesn’t just build an outstanding workplace, it also creates a better and more inclusive travel experience for everyone. Inclusion is at the heart of everything we do. It’s a place where you can make your mark and have a real impact in travel and tech.” 

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.

If your application is successful, your personal data may be used for a pre-employment screening check by a third party as permitted by applicable law. Depending on the vacancy and applicable law, a pre-employment screening may include employment history, education and other information (such as media information) that may be necessary for determining your qualifications and suitability for the position.