Data Scientist Technology Data Science London

Checkout Ltd; Greater London; On-site; GBP 75,000 - 110,000; Full time

Job summary

Checkout.com in the United Kingdom is seeking a Data Scientist to advance ML models and estimators that boost payment performance across our merchants portfolio. You will collaborate with Data Scientists, Product, and Engineering to deploy robust features and maintain observability for safe model launches.

You will design experiments, handle time‑based data leakage, and communicate results clearly, leveraging Python for model training and productionizing features across core products.

Qualifications

• 3+ years of experience developing machine learning models to solve business problems.
• Strong understanding of supervised ML algorithms, tuning, and performance evaluation.
• Experience with a range of feature engineering techniques (e.g., target encoding).
• Solid grasp of frequentist and Bayesian statistics for parameter estimation and experimentation.
• Experience in writing clean, production-grade Python code for both model training and inference.
• Excited to leverage LLMs for coding support and process optimisation to maximise personal and team productivity.

Responsibilities

• Contribute to the research and development of new ML models and estimators to boost core Acceptance Rate performance.
• Design and implement experiments to produce actionable insights, focusing on managing time‑based data leakage and ensuring robust model evaluation.
• Collaborate with other Data Scientists and engineers to productionise ML features, models, and evolve our evaluation and monitoring frameworks.
• Write high‑quality, interpretable Python code for feature engineering and model training, contributing directly to our core products.
• Communicate hypotheses, evaluation results, and monitoring dashboards clearly to both technical and non‑technical audiences.

Skills

Machine learning

Python

Experiment design

Feature engineering

Statistics

Communication

LLM usage

Tools

Databricks

Docker

GCP

AWS

Job description

Company Description

Checkout.com powers the payments behind many digital experiences. We are where the world checks out, enabling over 10 billion transactions yearly for more than a billion global shoppers. Whether you book a holiday, order food, renew a subscription, or shop online, our tech powers the payments. Our platform helps businesses deliver effortless digital experiences at scale. We move fast, think globally, and believe great teams are built by exceptional people with conviction, curiosity, and a desire to make an impact. With 20 offices across six continents and London as our HQ, we’re shaping the future of fintech and just getting started.

About the Role

Checkout.com is looking for a Data Scientist to join our ambitious team, focused on discovering, designing, and experimenting with new estimators, models, and features to boost payment performance across our merchants portfolio. You will work closely with Data Scientists, Product, and Engineering to enhance our core offering, protect customer lifetime value through network intelligence, and ensure safe model launches through robust observability.

Key Responsibilities

• Contribute to the research and development of new ML models and estimators to boost core Acceptance Rate performance.
• Design and implement experiments to produce actionable insights, focusing on managing time‑based data leakage and ensuring robust model evaluation.
• Collaborate with other Data Scientists and engineers to productionise ML features, models, and evolve our evaluation and monitoring frameworks.
• Write high‑quality, interpretable Python code for feature engineering and model training, contributing directly to our core products.
• Communicate hypotheses, evaluation results, and monitoring dashboards clearly to both technical and non‑technical audiences.

About You

• 3+ years of experience developing machine learning models to solve business problems.
• Strong understanding of supervised ML algorithms, tuning, and performance evaluation.
• Experience with a range of feature engineering techniques (e.g., target encoding).
• Solid grasp of frequentist and Bayesian statistics for parameter estimation and experimentation.
• Experience in writing clean, production‑grade Python code for both model training and inference.
• Excited to leverage LLMs for coding support and process optimisation to maximise personal and team productivity.

Nice to Have

• Experience with advanced data transformation techniques (e.g., lambda functions).
• Familiarity with, or hands‑on experience in, recommender systems, contextual bandits, or network intelligence applications.
• Experience in fintech, payments, or building cross‑disciplinary relationships for advice and guidance.
• Familiarity with the Unix shell, Databricks, Docker, and common cloud platforms (GCP or AWS).

Additional Information

Bring all of you to work. We create the conditions for high performers to thrive, through real ownership, fewer blockers, and work that makes a difference from day one. You’ll move fast, take on meaningful challenges, and be recognized for the impact you deliver. It’s a place where ambition gets met with opportunity, and where your growth is in your hands.

We work as one team and back each other to succeed. So whatever your background or identity, if you’re ready to grow and make a difference, you’ll be right at home here.

We want to set you up for success and make our process as accessible as possible. Please let us know if you need anything to make your experience or working environment more comfortable.

Life at Checkout.com. We understand that work is just one part of your life. Our hybrid working model offers flexibility, with three days per week in the office to support collaboration and connection.

Curious about what it’s like to be part of our team? Visit our Careers Page to learn more about our culture, open roles, and what drives us. For a closer look at daily life at Checkout.com, follow us on LinkedIn and Instagram.