Machine Learning Scientist - Trust & Safety jobs at Booking in Netherlands, Amsterdam

As a Software Engineer working on the AI Application Platform, you will work at the intersection of scalable backend systems and cutting-edge AI. You will have the opportunity to design and build the core platform that enables product teams to rapidly develop and deploy AI-powered experiences for millions of people. You will tackle complex performance and scaling challenges, shape the foundation of our AI infrastructure, and collaborate closely with ML engineers, data engineers, and data scientists to bring intelligent systems into production at scale.

Important aspects of the job can include:

• Design and evaluate architecture solutions for AI infrastructure, rapidly prototyping to validate key assumptions and guide decision-making.
• Explore, benchmark, and integrate new AI/ML tools and technologies to drive innovative engineering solutions that meet evolving business needs.
• Build and maintain scalable, reusable backend services that support real-time AI/ML inference, model deployment, and data pipelines.
• Collaborate closely with ML engineers, data engineers, and data scientists to bring AI/ML models into production and optimize system performance.
• Take end-to-end ownership of system reliability and operational excellence, including performance tuning, observability and incident management.
• Continuously grow technical and interpersonal skills through hands-on experience, knowledge sharing sessions, and industry events.

We have found that people who match the following requirements are the ones who fit us best:

• Experience in feature engineering, integrating AI/ML models into production systems, and understanding model behavior, performance and constraints.
• Experience building AI agents and components such as memory, context engineering, retrieval, and orchestration.
• Experience working in cross-functional teams alongside ML engineers, data scientists, and product stakeholders to bring AI/ML products to production.
• 7+ years of professional experience in software engineering, with a focus on backend or platform development.
• Experience building distributed systems at scale, with a focus on performance tuning, observability, and reliability best practices.
• Experience with scalable data storage systems (e.g. MySQL, Redis) and optimizing data access and caching for high-throughput applications.
• Proficiency in one or more server-side programming languages such as Java, Scala, or Python.
• Experience with containerization tools like Docker and Kubernetes, and deploying applications in cloud environments such as AWS or GCP.
• Ability to navigate ambiguity, take ownership of complex problems, and drive them to resolution.
• Bachelor's or Master’s degree in Computer Science, Engineering, or a related technical field, or equivalent industry experience.

• Annual paid time off and generous paid leave scheme including: parental (22-weeks paid leave), grandparent, bereavement, and care leave.
• Hybrid working including flexible working arrangements, working from home furniture and ergonomic support, and up to 20 days per year working from abroad (home country).
• A beautiful sustainable, that offers on-site meals, coffee, and snacks, multi-faith and breastfeeding rooms at the office.
• Commuting allowance and bike reimbursement scheme.
• Discounts & Wallet credits to spend on our products, upgrade to Booking.com Genius Level 3, and friends & family Booking.com discount vouchers.
• Free access to online learning platforms, development and mentorship programs.
• Global Employee Assistance Program, free Headspace membership.

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.

As a Machine Learning Scientist in Performance Marketing, 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 on top of the most prominent online travel agencies, 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.

Key Job Responsibilities and Duties

• Devise and develop state-of-the-art 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.

• Proven record in devising and developing 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 + 4 years of working experience, or PhD + 2 years of working experience), involved in the application of Machine Learning to business problems.

• Experience on multiple machine learning facets: working with large data sets, model development, statistics, experimentation, data visualization, optimization, software development.

• Experience collaborating cross functionally in the development of machine learning products (e.g. Developers, Commercial, Data Analytics, etc.).

• Very strong working knowledge of Python, SQL/BigQuery, Spark

• Excellent English communication skills, both written and verbal.

Booking.com’s Total Rewards Philosophy is not only about compensation but also about benefits. We offer a competitive , 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

Application Process:

• Let’s go places together:

• This role does not come with relocation assistance.

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.

A key leadership role in Performance Marketing department. You will lead a team of experienced Machine Learning Scientists, accountable for driving the next strategic directions for optimizing online bidding strategy on top of the most prominent online travel agencies, managing one of the largest performance marketing budgets in the industry, and ensuring Bookings.com’s competitive edge in the complex dynamics of the bidding marketplace and online auction mechanisms. This role requires a unique combination of deep theoretical expertise around optimization methodologies, auction theory and state of the art machine learning, together with extensive experience in driving solutions for real-world large scale optimization problems and business products.

Key Job Responsibilities and Duties:

• Leadership in developing the next strategic solutions and driving business impact for bidding and optimization of Booking ads on top of the leading online travel agencies - lead, coach and mentor a team of machine learning scientists at a fast pace environment of innovation and development of machine learning and optimization algorithms tailored to the performance marketing domain.

• Leadership in innovation management of the research cycle, involving POC, model development and large-scale AB testing phases, for driving customer engagement while maximizing the efficiency of performance marketing spend.

• Continuously driving measurable business impact, fully utilizing the various optimization levers in the bidding and optimization space

• Driving a culture of protagonism, ownership and craft excellence within the team and foster close collaborative relationships between the team and the larger organization

• Continuously grow and develop the talent in the team and facilitate ways of working that foster the foundations on top of which the team can deliver business impact

• Extensively work together with senior management to align on business objectives and financial goals

Role Qualifications and Requirements:

• Proven record in leading applicative research teams which own the development of innovative machine learning and optimization solutions for large-scale domains.

• Proficiency in large-scale optimization methodologies and auction mechanisms

• Proven record of teams development and building and maintaining a culture of high-pace innovation

• Proven Impact: A track record of delivering measurable business value through the development and implementation of large-scale machine learning models.

• Strong working knowledge of Python, SQL/BigQuery, Spark

• Excellent communication skills

• Level of Education: Master’s degree or PhD required (Computer Science, Engineering, Mathematics, Artificial Intelligence, Physics)

Booking.com’s Total Rewards Philosophy is not only about compensation but also about benefits. We offer a competitive , 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

Application Process:

• Let’s go places together:

• This role does not come with relocation assistance.

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.

Role Description:

You will play a key role to discover causal relationships in a wide variety of travel products and customers, challenge hidden assumptions and validate the robustness of conclusions to enable confident decisions at scale with real business actions.

Key Job Responsibilities and Duties:

• Responsible for fully owning the design and delivery of causal solutions based on business requirements, from idea-generation, validation, implementation to stakeholder communication. Deliver customer value with the right solutions.

• Keep a sharp eye on both the strengths and limitations of applied methodologies in real use cases. Proactively explore and research advanced statistical and causal techniques suitable for the business applications, and guide junior members as a force multiplier.

• Identify and manage stakeholders independently. Autonomously translate business challenges into proper data stories and solutions. Capable of communicating complex solutions to business stakeholders and craft peers beyond the team’s scope with in-time updates, clear visualization, accessible documentation and effective verbal language.

• Responsible for interpreting quantitative experiments and causal models to objectively guide key business decisions. Grow technical competency and spot opportunities to adopt more efficient approaches. Break down complex problems into tangible milestones to drive continuous improvements and actionable outcomes on product or strategy.

• Identify trends and behaviors from data to uncover hidden causal insights across business domains. Unlock the value of causal inference by bringing together end-to-end solutions. Learn to incorporate scalability, reproducibility and long-term orientation in the work. Embed causal techniques into the bigger picture for business takeaways and recommendations.

Qualifications & Skills:

• Experience working with dynamic project setup, multiple teams and stakeholders to align expectations and collaboration. Turning open-ended questions into clear milestones and agreed deliverables.

• Passionate in driving innovation for real applications with curious, humble and can-do attitudes.

• Proven ability to unpack real world causal questions, design modeling or experimentation solutions, and provide clear and actionable business recommendations with real influence.

• Experience to research and compare new methods and validate feasibility with real data. Clearly explain the reasoning behind technical choices, and open to peer review and discussions.

• Able to zoom in and out in problem solving. Willing to dig deep for exploration, and summarize reusable learnings and methodologies for scalable exploitation.

• Excellent communication skills for diverse audiences. Able to discuss complex technical problems in an accessible, business-friendly manner at all phases of the project.

• Proficient in handling large amounts of data and using causal model packages with Python, Snowpark, or R. Familiar with using causal packages. Produce well structured, readable and reproducible high quality code.

Booking.com’s Total Rewards Philosophy is not only about compensation but also about benefits. We offer a competitive , 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

Application Process:

This section should provide:

• Let’s go places together:

• This role does not come with relocation assistance.

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.

In this role, you will be responsible for high-impact projects aimed at measuring marketing effectiveness and optimizing the performance of our marketing spend. Projects may include (but not limited to) using econometric models to measure the ROI of online and offline Brand activities, design and analysis of non-randomized experiments, and measuring the incrementality of marketing spend, various marketing campaigns, and product / service offerings. The output of your work will be used to help inform the marketing strategy for the future of Booking.com. You will also work proactively with many stakeholders across different teams to set up measurement frameworks for various marketing activities to determine the success.

1. Responsible for owning the design and delivery of entire Data Science solutions based on business requirements, bringing them from the initial idea-generation phase to implementation independently.

2. Responsible for working autonomously on consuming data, preparing it for data science use, translating business problems to data stories and solving them effectively by applying suitable statistical data analysis and modeling methods. Leverages input from business stakeholders in all of the above to determine the right technical solutions to deliver customer value.

3. Responsible for working primarily within the scope of their team to deliver work that informs business decisions for the product / business topic they currently work on, occasionally collaborating across multiple teams.

4. Responsible for designing and interpreting quantitative experiments to objectively guide key business decision making.

5. Responsible for independently identifying and managing stakeholders in operational, project-based, and managerial roles. Effectively communicates, addresses stakeholder needs, and conveys complex analysis results in a clear manner. Begins to guide junior colleagues in stakeholder engagement.

6. Responsible for being flexible in adopting existing internal and external Data Science approaches, proposing and spotting opportunities to apply new approaches and expanding their technical competencies and their peer’s when a more efficient way presents itself.

7. Responsible for leveraging Data Science for impact while learning to incorporate scalability, reproducibility and long term orientation in their work.

8. Responsible for acting as a force multiplier for junior peers in the team by actively helping them with their craft through means of coaching, mentoring and setting a good example.

9. Responsible for contributing to the community of their area by supporting community projects aimed at making other data professional more effective, actively participating in community strengthening activities (ie. recruitment) and connecting with peers beyond their area.

10. ​​Must be knowledgeable about the larger data ecosystem at Booking and how it relates to the work they do.

11. Responsible for collaborating with peers in related crafts (ie. Data Engineering), anticipating data needs to ensure smooth progress of their individual projects.

12. Must be knowledgeable with the operational, tactical and strategic goals of their area (ie. track / vertical) and have high level knowledge of the goals of their wider area (ie. Business Unit).

13. Responsible for ensuring quality of their own work by validating it through peer review.

14. Responsible for influencing business decisions within their specific area (ie. product team).

• Strong knowledge and experience in causal inference with observational data, econometric and ML models, marketing attribution, and incrementality modeling

• Experience in experimentation: A/B testing, geo-testing, power analysis, sample size determination, minimum detectable effect sizes, familiarity with biases in experimentation, meta-analysis etc.

• Strong working knowledge of descriptive and inferential statistics.

• Experience solving real problems using data mining techniques and with statistical rigor

• Excellent communication skills

• Strong skills in translating business problems into data problems

• Strong stakeholder management

• Strong coding and data visualization skills

• Strong skills in storytelling with data

• Strong knowledge of data management (engineering, data pipelines, workflows)

• Strong knowledge of the possibilities and limitations of different types of data analysis and/or data science modeling

[Sample “Benefits and Perks” language - this may be used as a starting point, but must be edited each time to ensure alignment to local benefits]:

Booking.com’s Total Rewards Philosophy is not only about compensation but also about benefits. We offer a competitive , 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

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.

Key Job Responsibilities and Duties:

• Work in a multi-disciplinary team where you’ll take full ownership of turning discoveries and ideas into products through Machine Learning (incl. understanding product requirements, data discovery, model development and evaluation, to implementation of a full production pipeline for both batch and stream-based deployments).

• Use the ML model’s output to deliver both short-term commercial impact and longer-term differentiated business value and customer experience.

• Define and build proof-of-concepts to test new ideas and demonstrate their potential value to relevant stakeholders.

• Develop production-grade ML code for models, features, and pipelines, accounting for scalability, latency, realtime requirements, monitoring and retraining.

• 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.

• Actively contribute to Machine Learning at Booking.com through training, exploration of new technologies, interviewing, onboarding, and mentoring colleagues.

Qualifications & Skills:

• At least 4 years of relevant work experience. Experience in ranking, recommender systems, personalization, e-commerce, etc. is a plus.

• Masters, PhD, or equivalent experience in a quantitative field (Computer Science, Mathematics, Engineering, Artificial Intelligence, etc.).

• We prefer candidates with Deep Learning experience, especially when applied to large-scale datasets or sequential modelling. Experience with TensorFlow or PyTorch is a plus.

• Solid understanding of fundamental machine learning concepts, such as gradient boosting, neural networks, feature engineering, model evaluation, etc.

• Fluency in at least one programming language, with a strong preference for Python.

• Strong working knowledge of Spark and SQL.

• Experience with putting Machine Learning models in production is a plus.

• Excellent English communication skills, both written and verbal; the ability to convey your message to team members and other stakeholders.

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

• Annual paid time off and generous paid leave scheme including: parental (22-weeks paid leave), grandparent, bereavement, and care leave

• Hybrid working including flexible working arrangements, working from home furniture and ergonomic support, and up to 20 days per year working from abroad (home country)

• A beautiful sustainable , that offers on-site meals, coffee, and snacks, multi-faith and breastfeeding rooms at the office*

• Commuting allowance and bike reimbursement scheme

• Discounts & Wallet credits to spend on our products, upgrade to Booking.com Genius Level 3, and friends & family Booking.com discount vouchers

• Free access to online learning platforms, development and mentorship programs

• Global Employee Assistance Program, free Headspace membership

Application Process

• Let’s go places together:

• The interview process entails an initial screen by one of our Recruiters, and a total of 3 Business interviews (including a take home business case).

• This role does not come with relocation assistance.

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.

Order to Cash is looking for an experienced Data Scientist II to help design and run data science solutions to measure and optimize our O2C operations efforts across different pillars from collections, payouts and revenue operations.

• Responsible for owning the design and delivery of entire Data Science solutions based on business requirements, bringing them from the initial idea-generation phase to implementation independently.
• Responsible for working autonomously on consuming data, preparing it for data science use, translating business problems to data stories and solving them effectively by applying suitable statistical data analysis and modeling methods. Leverages input from business stakeholders in all of the above to determine the right technical solutions to deliver customer value.
• Responsible for working primarily within the scope of their team to deliver work that informs business decisions for the product / business topic they currently work on, occasionally collaborating across multiple teams.
• Responsible for designing and interpreting quantitative experiments to objectively guide key business decision making.
• Responsible for independently identifying and managing stakeholders in operational, project-based, and managerial roles. Effectively communicates, addresses stakeholder needs, and conveys complex analysis results in a clear manner. Begins to guide junior colleagues in stakeholder engagement.
• Responsible for being flexible in adopting existing internal and external Data Science approaches, proposing and spotting opportunities to apply new approaches and expanding their technical competencies and their peer’s when a more efficient way presents itself.
• Responsible for leveraging Data Science for impact while learning to incorporate scalability, reproducibility and long term orientation in their work.
• Responsible for acting as a force multiplier for junior peers in the team by actively helping them with their craft through means of coaching, mentoring and setting a good example.
• Responsible for contributing to the community of their area by supporting community projects aimed at making other data professional more effective, actively participating in community strengthening activities (ie. recruitment) and connecting with peers beyond their area.
• ​​Must be knowledgeable about the larger data ecosystem at Booking and how it relates to the work they do.
• Responsible for collaborating with peers in related crafts (ie. Data Engineering), anticipating data needs to ensure smooth progress of their individual projects.
• Must be knowledgeable with the operational, tactical and strategic goals of their area (ie. track / vertical) and have high level knowledge of the goals of their wider area (ie. Business Unit).
• Responsible for ensuring quality of their own work by validating it through peer review.
• Responsible for influencing business decisions within their specific area (ie. product team).

• Experience solving real problems using data mining techniques and with statistical rigor and translating business problems into data problems

• Knowledge and practical experience of Statistical Methods (e.g. Testing, GLM, Inference), Statistical/Machine Learning (e.g. Dimension Reduction, Clustering, Regularisation, Bagged/Boosted methods), Time Series, etc

• Strong experience of A/B Testing and a range of Experimentation methods

• Strong experience in data engineering concepts: ETL, data warehousing, data modeling, and data quality management

• Solid understanding of DBT, Snowflake, Spark, SQL, Python and/or R

• Solid understanding of data management (schema design, data pipelines, workflows)

• Strong stakeholder management

• Strong data visualization skills

• Strong skills in storytelling with data

• Proven understanding of the possibilities and limitations of different types of data analysis and/or data science modelling

Booking.com’s Total Rewards Philosophy is not only about compensation but also about benefits. We offer a competitive , 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

Application Process:

• Let’s go places together:

• Detailed instructions on post-application requirements including any required application materials, deadlines, portfolios, coding challenges, or other assessments as defined by BU or department.

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.