Senior AI/ML engineer in London

Flo is the world’s #1 health & fitness app on a mission to build a better future for female health. We are looking for an AI/ML Platform Engineer to join the AI Platform team. This team builds and maintains Flo's shared platform for artificial intelligence, enabling every product team to use AI safely, efficiently, and at scale.

In this role, you will work at the intersection of machine learning engineering and MLOps, owning both the development and operationalization of AI/ML systems. Your responsibilities will span from fine-tuning and optimising large language models to building and maintaining the infrastructure that enables rapid experimentation and reliable deployment at scale.

The AI Platform team acts as the central enabler of machine learning and AI initiatives across the organisation. Its mission is to reduce operational overhead and maximise ROI from ML use cases. The team builds and maintains critical infrastructure including LLM evaluation frameworks, model deployment pipelines, fine-tuning infrastructure, user profiles store, experiment tracking systems, and monitoring frameworks.

What you’ll be doing:

• Develop, fine-tune, and optimise large language models for domain-specific health applications.
• Design and maintain automated pipelines for model training, fine-tuning, evaluation, and deployment across diverse AI workloads.
• Build and enhance LLM evaluation frameworks for measuring model safety, medical accuracy, and performance.
• Implement CI/CD practices for ML/AI engineering workflows.
• Orchestrate seamless deployment of models, AI agents, and inference endpoints.
• Implement comprehensive monitoring for model performance, drift detection, AI safety metrics, and responsible AI compliance.
• Constantly improve technical capabilities by researching and implementing best practices in the rapidly evolving space of LLMs and generative AI.
• Work in a cross-functional setup alongside other Flo Teams.

Must have:

• 4+ years of professional experience in machine learning.
• Recent engineering experience with LLM infrastructure and tooling.
• Strong Python programming skills.
• Experience with modern ML infrastructure tools.
• Cloud platform expertise with one of the Hyperscalers (AWS, GCP, or Azure).
• Understanding of the entire ML/LLM development lifecycle.
• Ability to devise creative solutions to intricate technical challenges.
• Excellent communication skills and ability to collaborate with diverse teams.
• Commitment to responsible AI practices.

Nice to have:

• Experience with LLM fine-tuning techniques.
• Containerisation and orchestration experience.
• AI model serving experience.
• Infrastructure as Code experience.
• Experience building and managing data pipelines.
• AI safety and governance experience.
• Familiarity with statistical fundamentals.
• Experience in the MedTech or HealthTech domain.

How we work:

We’re a mission-led, product-driven team. We move fast, stay focused and take ownership. Debate is encouraged. Decisions are shared. We care about craft, ship with purpose, and always raise the bar.

What you’ll get:

• Competitive salary and annual reviews.
• Opportunity to participate in Flo’s performance incentive scheme.
• Paid holiday, sick leave, and female health leave.
• Enhanced parental leave and pay.
• Accelerated professional growth through world-changing work and learning support.
• Flexible office + home working.
• 5-week fully paid sabbatical at 5-year Floversary.
• Flo Premium for friends & family, plus more health, pension and wellbeing perks.

Diversity, equity and inclusion:

Our strength is in our differences. At Flo, hiring is based on merit, skill and what you bring to the role. We’re proud to be an equal opportunity employer, and we welcome applicants from all backgrounds, communities and identities.