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. Today, we are a FTSE 250 company, with offices in London, Paris, Barcelona, Milan, Edinburgh, and Madrid.

With our focus on growth in the UK and Europe, now is the perfect time to join us on this high‑speed journey.

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 recommendations 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

Our machine learning teams own the complete delivery lifecycle from ideation to production and work closely with stakeholders across the business to expand the impact of machine learning and AI throughout Trainline.

We are looking for Machine Learning Engineers to join our team and help shape the future of train travel. You’ll join 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.

• 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.

• Have an advanced degree in Computer Science, Mathematics, Statistics or a similar quantitative discipline.
• Are proficient with Python, including open‑source data libraries such as Pandas, Numpy, and Scikit‑learn.
• Have experience product ionising 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 Dev Ops 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 a broad understanding of data extraction, data manipulation and feature engineering techniques.
• Are familiar with statistical methodologies.
• Have great communication skills.

• Experience with the transport industry and/or geographical information systems (GIS).
• Experience with cloud infrastructure.
• Experience with Large Language Models (fine tuning, RAG, agents).
• Experience with graph technology and/or algorithms.

Enjoy private health and dental insurance, a generous work‑from‑abroad policy, a 2‑for‑1 share purchase plan, an electric vehicle scheme, extra festive time off, and family‑friendly benefits. We prioritize career growth with clear career paths, transparent pay bands, personal learning budgets, and regular learning days. The hybrid model requires staff to work from the office a minimum of 60 % of their time over a 12‑week period and offers a 28‑day work‑from‑abroad policy.

• Think Big – building the future of rail.
• Own It – focusing on every customer, partner and journey.
• Travel Together – working as one team.
• Do Good – making a positive impact.

Trainline is committed to creating inclusive places to work, where everyone belongs and differences are valued and celebrated. We welcome all forms of diversity – gender, ethnicity, sexuality, disability, nationality and diversity of thought.