Senior AI/ML engineer

The role

You will build and ship LLM-powered product features including personalized recommendations, conversational insights, and AI-generated notifications. You will focus on GenAI feature behavior such as relevance, quality, latency, and safety while contributing to infrastructure work.

What you will do

• Build and ship LLM-powered product features
• Reduce perceived and actual response latency
• Iterate on prompt design and calibration
• Enable A/B testing for model and prompt changes
• Contribute to synthetic Q&A generation and evaluation dataset design
• Contribute to Databricks, AWS (EKS), Terraform, or CI/CD work
• Collaborate with Product, Security, Analytics, and Medical teams

Required qualifications

• 7+ years of software engineering
• Recent hands-on experience building product features backed by LLMs
• Experience with at least one of: prompt engineering, LLM evaluation, fine-tuning, or model serving
• Strong Python
• Comfort working with APIs/SDKs that wrap LLM calls, prompt templates, and structured outputs
• Track record of shipping user-facing features with attention to latency, tone, and quality of AI output
• Comfort picking up new infrastructure tools (Databricks, AWS, Terraform, GitHub Actions)

Nice to have

• LLM evaluation frameworks (judges, graders, calibration methodology) or fine-tuning techniques (LoRA, RLHF/DPO, model distillation)
• Prompt optimisation frameworks (DSPy or similar)
• Feature stores or personalization/ranking experience
• Healthcare, regulated-industry, or safety-critical AI systems experience
• Data engineering fundamentals (Spark, Delta tables, Parquet)

Benefits

• 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 for maternity, paternity, same-sex and adoptive parents
• Accelerated professional growth through world-changing work and learning support
• 5-week fully paid sabbatical at 5-year Floversary
• Flo Premium for friends & family
• Health, pension and wellbeing perks

About the company

Flo is the world’s #1 health & fitness app with 80M+ monthly users. It is building the next generation of digital health that is AI-powered, privacy-first, and clinically backed.