Machine Learning Engineer

About us

We are champions of rail, inspired to build a greener, more sustainable future of travel. Trainline enables millions of travellers to find and book the best value tickets across carriers, fares, and journey options through our highly rated mobile app, website, and B2B partner channels.

Machine learning and AI at Trainline

Machine learning and AI are at the core of how Trainline is transforming travel, helping millions of customers make smarter, more sustainable journeys every day. Our ML models and AI solutions power critical aspects of our platform, including:

• Advanced search and recommendation capabilities across our mobile and web applications
• Pricing and routing optimisations to find the best fares for customers
• Personalised user experiences enhanced by agentic AI
• Data‑driven digital marketing systems
• AI agents improving customer support

About the role

We are looking for Machine Learning Engineers to join our team to shape the future of train travel. You’ll be joining a high‑performing, deeply technical community of Machine Learning Engineers, Data Scientists, and Data Engineers to tackle complex problems by combining Trainline’s rich datasets with cutting‑edge algorithms. What unites our team is an expertise in the field, a love of what we do, and the desire to create impactful solutions to support Trainline’s goals of encouraging sustainable travel. As a part of Trainline you will be joining an environment where learning and development is top priority. You will have the opportunity to work with fellow ML & AI enthusiasts on large‑scale production systems, delivering highly impactful products that make a difference to our millions of customers.

Key responsibilities

• Work in cross‑functional teams combining data scientists, software, data and machine learning engineers, and product managers
• Design and deliver machine learning models and/or AI solutions at scale that drive measurable impact for Trainline
• Own the full end‑to‑end machine learning delivery lifecycle including data exploration, feature engineering, model selection and tuning, offline and online evaluation, deployments and maintenance
• Partner with stakeholders to propose innovative data products that leverage Trainline’s extensive datasets and state‑of‑the‑art algorithms
• Create the tools, frameworks and libraries that enable the acceleration of our ML & AI product delivery and improve our workflows
• Take an active part in our AI and ML community and foster a culture of rigorous learning and experimentation

What we’re looking for

• Have an advanced degree in Computer Science, Mathematics, Statistics or a similar quantitative discipline
• Are proficient with Python, including open‑source data libraries (e.g., Pandas, Numpy, Scikit‑learn)
• Have experience productionising machine learning models and/or AI solutions
• Are an expert in one of predictive modelling, classification, regression, optimisation, NLP algorithms or recommendation systems
• Have experience with Spark
• Have knowledge of DevOps technologies such as Docker and Terraform and ML Ops practices and platforms like ML Flow
• Have experience with agile delivery methodologies and CI/CD processes and tools
• Have broad understanding of data extraction, data manipulation and feature engineering techniques
• Are familiar with statistical methodologies
• Have great communication skills

Nice to have

• Experience with transport industry and/or geographical information systems (GIS)
• Experience with cloud infrastructure
• Experience with large language models (fine‑tuning, retrieval‑augmented generation, agents)
• Experience with graph technology and/or algorithms

Benefits and working conditions

We offer private health and dental insurance, a generous work‑from‑abroad policy, 2‑for‑1 share purchase plans, an EV scheme, extra festive time off, and family‑friendly benefits. We prioritise career growth with clear career paths, transparent pay bands, personal learning budgets and regular learning days. We operate a hybrid model, asking that Trainliners work from the office a minimum of 60 % of the time over a 12‑week period, and we also have a 28‑day work‑from‑abroad policy.

Equal Opportunity Employer

We know that having a diverse team makes us better and helps us succeed. We are committed to creating inclusive places to work, where everyone belongs and differences are valued and celebrated.