Senior Data Scientist

Salary: £45,000 - 83,000 per year

Requirements:

• 5+ years of experience designing, building, and maintaining machine learning models to solve complex, large-scale business problems.
• Deep understanding of frequentist and Bayesian statistics, plus supervised and unsupervised modelling techniques.
• Proven experience modelling complex interactions, such as cluster or network effects.
• Expertise in model explainability to tune feature engineering and understand feature interactions.
• Ability to write high-quality, production-grade Python code and collaborate effectively with non-technical stakeholders.
• Proficient in leveraging LLMs for coding support and process optimisation to maximise personal and team productivity.
• Adept at tuning technical communication for broad audiences.
• Proven ability to build trusting relationships with product stakeholders and deeply understand business models.
• Experience with distributed general-purpose cluster-computing is nice to have.
• Proven experience designing and deploying recommender systems, contextual bandits, or network intelligence applications is nice to have.
• Experience in fintech, payments, or similar domains is nice to have.
• Experience with Docker, AWS/GCP, and modern ML deployment practices is nice to have.

Responsibilities:

• Lead projects and architecture design for multi-objective optimisation and scalable models.
• Create custom loss functions, evaluation, and tuning frameworks that reflect complex business problems.
• Collaborate with product stakeholders to align technical strategy with business goals and resolve blockers across the team.
• Apply efficient data transformations using distributed computing, such as Spark and Dask, and ensure robust test coverage for production systems.
• Mentor junior team members and use model explainability methods to drive feature performance improvements.
• Enhance payment flow through data and ML services and advance the complex problem of multi-objective optimisation.
• Work closely with other Senior and Staff Data Scientists to shape the architecture of our decisioning systems.

Technologies:

• AWS
• Docker
• Flow
• GCP
• Support
• Machine Learning
• Network
• Python
• Spark
• Cloud

More:

We are Checkout.com, a global fintech company powering digital experiences for major brands and enabling over 10 billion transactions annually for more than one billion shoppers worldwide. Our platform supports ambitious businesses with seamless payments at scale, and we operate across 20 offices on six continents with London as our HQ. For this Senior Data Scientist role, we offer a hybrid working model with three days per week in the office, high ownership, fewer blockers, and meaningful work from day one. We value collaboration, growth, and accessibility, and were building our future with fast-moving, high-performing teams.

last updated 35 week of 2026