Principal Machine Learning Scientist

United States Digital Space LLC; Greater London; On-site; GBP 120,000 - 170,000; Full time

Job summary

Tripadvisor is seeking a Principal Machine Learning Scientist to lead the ML strategy powering discovery and travel recommendations. You will bridge cutting-edge research and production systems to impact billions of interactions.

You will own the technical roadmap for search, retrieval, ranking, and recommendations, mentor a team of scientists, and advocate for scalable, privacy-conscious ML practices. This role demands deep expertise in multi-task ranking, sequential modeling, and

Qualifications

• Ph.D. or Master’s in Computer Science, ML, Statistics or a quantitative field.
• 8+ years of industry experience deploying large-scale ML models.
• Proven track record shipping systems at scale to millions of users.
• Experience with multi-task learning and MMoe architectures.
• Proficiency with Python and ML frameworks (TF/PyTorch) and distributed systems.

Responsibilities

• Lead technical roadmap for Search, Retrieval, Ranking, and Recommendations.
• Design and scale next‑gen recommendation and ranking models.
• Oversee low-latency, high-throughput data pipelines for real-time processing.
• Mentor senior and mid-level ML scientists and foster best practices in MLOps.
• Collaborate with product and engineering teams to optimize multi-task objectives.

Skills

SOTA Retrieval & Ranking

Sequential Modeling

Representation Learning

Python & DL Frameworks

Distributed Computing

Education

Ph.D. or Master’s in CS/ML/Statistics

Tools

TensorFlow

PyTorch

Spark

Ray

AWS/GCP

Job description

About Tripadvisor

The Tripadvisor Group connects people to experiences worth sharing, and aims to be the world's most trusted source for travel and experiences. We leverage our brands, technology, and capabilities to connect our global audience with partners through rich content, travel guidance, and two-sided marketplaces for experiences, accommodations, restaurants, and other travel categories. The subsidiaries of Tripadvisor, Inc. (Nasdaq: TRIP), include a portfolio of travel brands and businesses, including Tripadvisor, Viator, and TheFork.

About the role:

As a Principal Machine Learning Scientist , you will be the technical anchor for our core discovery engine. You will lead the machine learning strategy and execution that powers how millions of users search for, discover, and organize their complex travel itineraries. This is a high-impact role bridging the gap between cutting-edge AI research and production-grade engineering, directly influencing multi-objective business outcomes like user engagement, booking conversion, etc.

You will tackle complex, ambiguous problems at the intersection of deep multi-task ranking, sequential user modeling, and graph-based travel recommendations. If you are passionate about building state-of-the-art AI systems and mentoring a high-performing team of scientists, this role is for you

What You'll Do

• Technical Leadership & Execution: Drive the technical roadmap for Search, Retrieval, Ranking, and Recommendation systems within the Trips vertical. Translate high-level business goals into concrete ML architectures and scalable production systems.
• Advanced Algorithm Innovation: Design, prototype, and scale next-generation recommendation and ranking models. Solve complex, non-linear travel journeys by utilizing sequential recommenders, representation learning, and deep multi-objective frameworks.
• System Architecture & Scalability: Oversee the deployment of low-latency, high-throughput retrieval and ranking pipelines (e.g., multi-stage retrieval, vector search) capable of processing billions of travel data points (reviews, photos, bookings, user intent) in real-time.
• Cross-Functional Collaboration: Partner closely with Product Managers, Engineering Leads, and Data Science peers to optimize multi-task business objectives simultaneously. Act as the primary technical authority for ML initiatives within the Trips vertical.
• Talent Multiplier: Mentor and coach senior and mid-level ML scientists. Foster a culture of technical excellence, driving best practices for MLOps, rigorous A/B testing, data privacy, and code quality.

Skills & Experience:

• Education: Ph.D. or Master's degree in Computer Science, Machine Learning, Statistics, or a highly quantitative field.
• Experience: 8+ years of industry experience developing and deploying large-scale ML models in a production environment, with a proven track record of shipping systems at the scale of millions of active users.
• Core Technical Expertise:
  • SOTA Retrieval & Ranking: Practical experience with Multi-Task Learning (MTL), Multi-gate Mixture-of-Experts (MMoE), or similar architectures optimized for multi-objective optimization.
  • Sequential & Temporal Modeling: Hands-on experience building sequential recommendation systems that capture real-time user session dynamics and long-term historical preferences.
  • Advanced Representation Learning: Deep understanding of embedding generation, deep semantic retrieval, and multi-modal representation learning.
• Technical Stack: Mastery of Python and deep learning frameworks (TensorFlow, PyTorch) alongside hands-on experience with distributed computing (Spark, Ray) and cloud infrastructure (AWS/GCP).

Desired:

Graph Neural Networks (GNNs):