Data Scientist

Job Description

Who are OnBuy?

OnBuy are an online marketplace who are on a mission of being the best choice for every customer, everywhere.

We have recently been named one of the UK's fastest-growing tech companies in the Sunday Times 100 Tech list.

All achievements we are very proud of, but we don't let that go to our head. We are all laser focused on our mission and understand the huge joint effort ahead of us needed to succeed.

Working at OnBuy:

We are a team of driven and motivated people who thrive when working at pace. To succeed at OnBuy you need to take charge and fully own your responsibilities, rolling your sleeves up when needed to 'get it done'. Working at OnBuy you are surrounded by so much opportunity, but you must possess the ability to stay focused and prioritise ruthlessly. Most importantly, you will thrive in an ever-changing environment as we are constantly evolving.

At OnBuy, you're not just a number or another cog in a machine. We are creating something really special, and you have the opportunity to affect meaningful change and have your voice heard. We are a close team, who have the opportunity to learn and grow as OnBuy evolves.

About the Role
As our Data Scientist you will help drive growth and improve customer experience across OnBuy. You’ll work closely with Product, Marketing and Seller teams to turn data into actionable insight, build predictive models, and influence commercial decisions at pace.

Key responsibilities:

• Develop and deploy data science models to support key e-commerce use cases such a purchase propensities, marketing attribution, product recommendations and retention risk.
• Design and analyse experiments (A/B and multivariate testing) to evaluate product and marketing initiatives.
• Translate business problems into clear analytical questions and data science solutions.
• Continuously monitor model performance and refine models to ensure accuracy and effectiveness in an evolving ecomms landscape.
• Communicate insights and model outputs clearly to non-technical stakeholders, influencing decisions.
• Collaborate with Data Engineers to ensure models are scalable, reliable and production ready.
• Work closely with analysts to share best practice, provide coaching, and raise overall data capability across the team.
• Support a culture of data-driven decision making across the business.

Requirements

Essential

• Degree in Data Science, Mathematics, Computer Science, or a related field.
• Over 2 years data science experience ideally within an e-commerce, digital, or consumer business.
• Ability to focus on business outcomes (growth, conversion, retention, margin), not just models — and to prioritise work that delivers measurable impact.
• Confident in statistics, experimentation, and machine learning, with the judgement to choose the right level of complexity for the problem.
• Understanding of customer behaviour, funnels, marketing channels, pricing, and product performance — or the ability to learn this quickly.
• Can explain complex concepts simply, tell a compelling data story, and influence non-technical stakeholders to act on insights.
• Works effectively with analysts, data engineers, product and marketing teams — building reusable, well-documented, scalable solutions and raising capability around them.
• Excellent Python skills (e.g. pandas, numpy, scikit-learn, statsmodels) and strong expertise in SQL for data querying, manipulation, and transformation.
• Familiarity with cloud data platforms (e.g. BigQuery, Snowflake, Databricks).
• Excellent problem-solving skills.

Desirable:

• Experience with recommendation systems, forecasting, or causal inference.
• Knowledge of marketing analytics (attribution, MMM, incrementality).
• Experience with data visualisation tools.
• Understanding of version control using Git.

Benefits

The salary on offer for this role is £65000- £70000 depending on experience.

We also offer the following benefits:

• Company Equity- In return for helping us to grow, we’ll offer you company equity, meaning you own a piece of this business we are all working so hard to build.
• 25 days annual leave + Bank Holidays
• 1 extra day off for your Birthday
• Employee Assistance Programme
• Perks at Work benefit platform
• Opportunities for career development and progression

Plus in return for helping us to grow, we’ll offer you company equity, meaning you own a piece of this business we are all working so hard to build.

Our Commitment

OnBuy is an equal opportunities employer. We are dedicated to creating a fair and transparent workforce, starting with a recruitment process that does not discriminate on the basis of gender, sexual orientation, marital or civil partnership status, pregnancy or maternity, gender reassignment, race, colour, nationality, ethnic or national origin, religion or belief, disability, or age.