{"id":2440807,"url":"https://alion.io/job/trainline-junior-machine-learning-engineer-2","title":"Junior Machine Learning Engineer","company":{"id":4051,"name":"Trainline","domain":"thetrainline.com","url":"https://alion.io/company/trainline","size_band":"501-1000","is_staffing_agency":false,"employer_type":"direct","is_intermediary":false,"listed_via":null,"ats_vendor":"Ashby","truth_index":null},"role":"AI/ML","role_family":"AI/ML","seniority":"junior","employment_type":"full_time","work_mode":"on_site","remote_scope":null,"remote_scope_basis":null,"remote_working_hours":null,"hiring_geo_confidence":"structured","locations":["London, United Kingdom"],"countries":["GB"],"hiring_countries":[],"hiring_countries_total":0,"salary":{"min":40000,"max":50000,"currency":"GBP","period":"year","gross":null,"usd_annual":66083},"salary_estimate":null,"experience_years_min":null,"visa_sponsorship":false,"relocation_package":false,"has_equity":false,"technologies":[{"name":"Agile","optional":false},{"name":"AI Agents","optional":false},{"name":"CI/CD","optional":false},{"name":"Docker","optional":false},{"name":"Machine Learning","optional":false},{"name":"MLFlow","optional":false},{"name":"NumPy","optional":false},{"name":"Pandas","optional":false},{"name":"Python","optional":false},{"name":"Recommender Systems","optional":false},{"name":"Scikit-learn","optional":false},{"name":"Spark","optional":false},{"name":"Terraform","optional":false},{"name":"Amazon ECS","optional":true},{"name":"AWS","optional":true},{"name":"Fine-tuning","optional":true},{"name":"LightGBM","optional":true},{"name":"NLP","optional":true},{"name":"pySpark","optional":true},{"name":"RAG","optional":true},{"name":"Reinforcement Learning","optional":true},{"name":"TensorFlow","optional":true}],"status":"live","first_seen_at":"2026-10-13T09:03:45Z","employer_posted_date":"2026-10-13","last_verified_at":"2026-10-13T23:43:57Z","board_verified":true,"closed_at":null,"days_open":0,"trust":{"level":"ok","repost_count":null,"flags":[],"days_open":0},"description":"About us\nAt Trainline, our purpose is to empower greener travel choices, connecting people and places. 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.\nGreat journeys start with Trainline\nWe’re Europe’s leading independent rail platform, helping millions of travellers find and book the best-value rail and coach journeys across our app, website and partner channels.\nOur job is to make the green travel choice the best choice. By building a better train travel experience, we help more people choose rail - creating a positive impact for customers, our business and the planet.\nWe’re a team of more than 1,000 Trainliners from over 50 nationalities, working across London, Paris, Barcelona, Milan, Edinburgh and Madrid. Now is a brilliant time to join us and help shape the future of travel.\nIntroducing Machine Learning and AI at Trainline\nMachine learning is at the heart of Trainline's mission to help millions of people make sustainable travel choices every day. Our ML models power critical aspects of our platform, including:\nAdvanced search and recommendations capabilities across our mobile and web applications\n\nPricing and routing optimisations to find the best fares for customers\n\nPersonalised user experiences enhanced by Reinforced Learning Agents & Generative AI\n\nData-driven digital marketing systems\n\nAI agents improving customer support\n\nOur machine learning teams own the complete delivery lifecycle from ideation to production. We work closely with stakeholders across the business to expand the understanding and impact of machine learning and AI throughout Trainline.\nThe Role:\nWe are looking for a Junior Machine Learning Engineer to join our team help shape the future of train travel. You will be part of a highly innovative AI and ML platform working alongside engineers, scientists and product managers to tackle complex challenges 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.\nAs 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 enthusiasts on large-scale production systems, delivering highly impactful products that make a difference to our millions of users.\nAs a Junior Machine Learning Engineer at Trainline you will...\nWork in cross-functional teams combining data scientists, software, data and machine learning engineers, and product managers\n\nDesign and deliver machine learning models at scale that drive measurable impact for our business\n\nOwn 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\n\nWork with MLE Team and Stakeholders to help design and deliver data driven products using Trainline's extensive datasets and modern machine learning techniques\n\nCreate the tools, frameworks and libraries that enables the acceleration of our ML products delivery and improve our workflows\n\nTake an active part in our AI and ML community and foster a culture of rigorous learning and experimentation\n\nWe'd love to hear from you if you...\nHave an advanced degree in Computer Science, Mathematics or a similar quantitative discipline\n\nAre proficient with Python, including open-source data libraries (e.g Pandas, Numpy, Scikit learn etc.)\n\nHave experience productionising machine learning models\n\nAre an expert in one of predictive modeling, classification, regression, optimisation or recommendation systems\n\nHave experience with Spark\n\nHave knowledge of DevOps technologies such as Docker and Terraform and ML Ops practices and platforms like ML Flow\n\nHave experience with agile delivery methodologies and CI/CD processes and tools\n\nHave a broad of understanding of data extraction, data manipulation and feature engineering techniques\n\nAre familiar with statistical methodologies.\n\nHave good communication skills\n\nNice to have\nUnderstanding and/or hands-on experience of Reinforcement Learning theories, frameworks, and algorithms\n\nExperience with cloud infrastructure\n\nExperience with Large Language Models (fine tuning, RAG, agents)\n\nExperience with graph technology and/or algorithms, understanding of NLP algorithms\n\nOur technology stack\nPython and associated ML/DS libraries (scikit-learn, NumPy, LightGBM, Pandas, TensorFlow, etc...)\n\nPySpark\n\nAWS cloud infrastructure: EMR, ECS, Athena, etc.\n\nMLOp/DevOps: Terraform, Docker, Airflow, MLFlow, NewRelic\n\nThe interview process\nRecruiter Call (30 minutes)\n\nMeeting a Machine Learning Manager (30 minutes)\n\nTechnical Interview with 2 x Engineers (90 mins)\n\nFinal Interview with the Head of (30-45 mins)\n\nMore information:\nEnjoy fantastic perks like private healthcare & dental insurance, a generous work from abroad policy, 2-for-1 share purchase plans, an EV Scheme to further reduce carbon emissions, extra festive time off, and excellent family-friendly benefits.\nWe prioritise career growth with clear career paths, transparent pay bands, personal learning budgets, and regular learning days. Jump on board and supercharge your career from day one!\nWe're operating a hybrid model and ask that Trainliners work from the office a minimum of 60% of their time over a 12-week period. We also have a 28-day Work from Abroad policy.\nOur values represent the things that matter most to us and what we live and breathe everyday, in everything we do:\nThink Big - We're building the future of rail\n\nOwn It - We focus on every customer, partner and journey\n\nTravel Together - We're one team\n\nDo Good - We make a positive impact\n\nWe know that having a diverse team makes us better and helps us succeed. And we mean all forms of diversity - gender, ethnicity, sexuality, disability, nationality and diversity of thought. That's why we're committed to creating inclusive places to work, where everyone belongs and differences are valued and celebrated.\nInterested in finding out more about what it's like to work at Trainline? Why not check us out on LinkedIn, Instagram and Glassdoor!","description_format":"text","description_chars":6362,"description_truncated":false,"requirements":{"experience_years_min":null,"management_years_min":null,"team_size_min":null,"manages_managers":false,"education":{"level":"bachelor","optional":false},"security_clearance":false,"languages":[]},"benefits":["Dental insurance"],"hiring_locations":[],"hiring_excludes":[],"relocation_offered":false,"industries":["Ticketing","Travel Technology"],"lifecycle":[{"event":"open","at":"2026-10-13T11:59:42Z"}],"visa":[],"liveness":{"score":86,"band":"hot","label":"Hiring now","p_open":1,"p_active":0.86,"p_room":1,"age_days":0,"expected_fill_days":40,"reasons":["conf:3","win:early","comp:junior"],"computed_at":"2026-10-14T03:04:29Z"},"pay":{"stated_usd_annual":66083,"is_top_pay":false},"html_url":"https://alion.io/job/trainline-junior-machine-learning-engineer-2","json_url":"https://alion.io/job/trainline-junior-machine-learning-engineer-2.json","meta":{"generated_at":"2026-10-14T03:04:29Z","cache_seconds":300,"methodology":"https://alion.io/methodology","terms":"https://alion.io/terms","contact":"https://alion.io/contact","api":"https://alion.io/developers","about":"Alion is a live layer of people, companies and AI agents: who they are, whether they are real and active right now, what they do and how to work with them, readable by people and by agents and paid per call.","catalog":"https://alion.io/catalog.json","usage":{"tier":"crawler_verified","counted_by":"address","units_charged":1,"used_today":4757,"day_limit":null,"remaining_today":null,"minute_limit":300,"resets_at":"2026-10-15T00:00:00Z"}},"offers":[{"id":"company.slices","title":"One company in depth, by slice","status":"live","price":{"credits":0.02,"usd":0.002,"plus_per_slice":{"credits":0.05,"usd":0.005}},"unit":"per company, plus each slice with data","note":"the employer in depth","call":{"mcp_tool":"get_company","arguments":{"id":4051},"rest":"https://alion.io/mcp/rest/get_company?id=4051"},"human":"https://alion.io/catalog?offer=company.slices&for=job%2Ftrainline-junior-machine-learning-engineer-2"},{"id":"market.stats","title":"A market slice: pay, demand and time to fill","status":"live","price":{"credits":1,"usd":0.1},"unit":"per slice","note":"pay, demand and time to fill for this role and place","call":{"mcp_tool":"market_stats"},"human":"https://alion.io/catalog?offer=market.stats&for=job%2Ftrainline-junior-machine-learning-engineer-2"},{"id":"job.search","title":"Open jobs by role, technology, place, pay and visa","status":"live","price":{"credits":0.02,"usd":0.002},"unit":"per posting in a list","note":"similar open postings","call":{"mcp_tool":"search_jobs"},"human":"https://alion.io/catalog?offer=job.search&for=job%2Ftrainline-junior-machine-learning-engineer-2"},{"id":"company.verify","title":"Is this company real and active right now","status":"pilot","price":null,"unit":"per company","request":{"url":"https://alion.io/catalog/request","method":"POST","body":"{\"offer\": \"company.verify\", \"for\": \"job/trainline-junior-machine-learning-engineer-2\", \"note\": \"what you need it for\"}"},"human":"https://alion.io/catalog?offer=company.verify&for=job%2Ftrainline-junior-machine-learning-engineer-2"}]}