Senior Machine Learning Engineer

Who you are

• You like using machine learning to solve challenging problems in a complex domain
• You enjoy working closely with product, design and the analysts who use what you build, and you take the lead in turning their feedback into technical decisions
• You have hands-on experience with model serving (small models and LLMs), agent orchestration and retrieval systems, and a thoughtful, current view on effective workflows in this space
• You care about engineering fundamentals: writing code that's clean and maintainable, and you hold the people around you to that same bar
• You're comfortable owning ambiguity, setting direction, and mentoring others in a fast-paced environment
• Due to the nature of our work and the clients we support, applicants must be eligible to obtain UK security clearance. We are currently only able to consider applicants who are nationals of a NATO member state, Australia, or New Zealand
• Technical excellence (working on production systems at scale, research that was used, or end-to-end ownership in an early-stage role)
• Hands-on experience with model serving (small models and LLMs), agent orchestration and retrieval systems
• Rigour in evaluation and benchmarking
• Strong engineering fundamentals: ability to write clean, maintainable code and design robust systems
• Comfort with a fast-paced environment and clear ownership
• Experience with modern coding agents and thoughtful views on effective workflows
• Early-stage start-up experience
• Building agentic tools and harnesses
• Working on domain specific modelling problems
• Clear writing, systematic thinking and strong communication

What the job involves

• We are looking for a Senior ML Engineer to join ExTrac's Machine Learning team, which owns our modelling capabilities end-to-end
• You will partner directly with software engineering and product design to understand requirements, design and run model evaluations, integrate optimised workflows into production pipelines and ensure results remain reliable at scale
• You will architect cutting-edge agentic systems for large-scale analysis of the geopolitical landscape, train and evaluate domain-specific models for the unique problems our customers face and work with design and engineering to bring them into the product
• Alongside domain experts, you will translate research into practical solutions for analysts operating at the frontier of their field
• In this role, you will lead technical direction on major initiatives, set standards across the team, and mentor others. You will take projects from prototype to reliable production deployment, collaborate closely with the engineers who design the data collection and processing backend, and engage directly with senior stakeholders
• We look for people who enjoy challenging problems, keep learning and build systems that scale. We value low ego, genuine ownership and a passion for applying AI to high-stakes intelligence challenges
• Design systems that balance research velocity with real product and production constraints
• Make technical decisions on model selection, training approaches, evaluation and deployment
• Deliver production-ready systems at scale, combining research rigour with pragmatic engineering
• Take projects from early exploration through to reliable deployment
• Uphold high standards for architecture, code quality, evaluation and research practice
• This role puts you at the frontier of applied AI for high-stakes decision-making, with real influence over how ExTrac's agentic systems are built and where they go next
• Strong performance here means deeper ownership of technical direction across the ML team, a bigger hand in setting the standards others are held to, and a path toward specialised domain AI leadership or broader technical leadership, depending on what you want to grow into

The application process

• Initial Intro Interview - 30 Minutes
• Technical Assessment - 45 minutes
• System Design Assessment - 45 minutes
• Founder interview - 30 Minutes

Benefits

• Flexible working: work where you work best, with the opportunity to spend 2-5 days a week working with the team in our central London office
• An annual individual learning and development budget of £500
• A generous private healthcare package
• Cycle to work scheme
• 33 days of annual leave
• Sabbatical leave offer
• Enhanced pension contributions
• Enhanced parental leave
• Workplace nursery scheme
• Regular team lunches and socials
• An annual individual learning and development budget
• A generous private healthcare package
• On-target earnings (OTE) structure tied directly to customer outcomes
• A role that combines mission-driven purpose with cutting-edge technology in a fast-growing company.