Senior Machine Learning Engineer

Description

The company has more than 500M downloads and over 80M monthly users, and has operated for 10 years while still growing quickly.

The company is ranked the number one health and fitness app worldwide and aims to build a better future for female health. It received a $200M investment led by General Atlantic and reached a $1B valuation in 2024.

It has 7M paid subscribers and the top-rated experience in the App Store's health category. It is now building AI-powered, privacy-first, clinically backed digital health products that help users understand their bodies better.

The team is hiring a Machine Learning Engineer to build new features that combine medical expertise, technical depth, quick adoption of new technology such as LLMs, product knowledge, and a close understanding of user needs. Candidates who enjoy generative AI and want to deliver value to users are encouraged to apply.

Responsibilities

• Explore, build and test complex ML and AI systems that improve female health.
• Use leading LLM and generative AI methods to create solutions that are medically safe and scale well.
• Own ML and AI products from start to finish, moving quickly to build and test product hypotheses.
• Build the long-term infrastructure needed to serve generative AI features across the company and turn the AI strategy into working products.
• Keep your technical skills current by researching and applying best practices in the fast-changing field of LLMs.
• Work in a cross-functional team with ML, backend and QA engineers, product managers and analysts.

Requirements

• 7+ years of professional machine learning experience.
• Proven experience building and deploying large-scale machine learning models.
• Ability to find creative solutions to complex technical problems, including designing systems and explaining ML and LLM pipelines.
• Strong Python skills for building and deploying models efficiently.
• Experience with both traditional ML and modern LLM frameworks.
• Understanding of the full ML and LLM lifecycle, including CI/CD, version control, testing, MLOps and LLMOps, and agile methods.
• Experience building and managing data pipelines with tools such as Apache Spark.
• Strong communication skills and the ability to work well with diverse teams.
• Commitment to responsible AI, including fairness, accountability and transparency.
• Advanced degree in Computer Science, Mathematics or a related field.
• Familiarity with statistics and measurement, and experience running and evaluating A/B tests.
• Data visualisation skills.
• Experience in the MedTech domain.
• Bonus: experience with large-scale LLM applications.

Conditions

The team is mission-led and product-driven. It moves fast, stays focused and takes ownership from the initial brief through to build and impact. Debate is welcome, decisions are shared, and the team cares about craft and keeps raising the bar.

You will work with people who take the work seriously without taking themselves too seriously. The role requires commitment, resilience and the drive to keep going when things get hard, because better health outcomes are worth it.

Salary range: £130,000 - £180,000 GBP per year, which may vary based on skills and experience.

Hybrid working, with 3 days per week in the office.

Benefits

• Competitive salary with annual reviews.
• Eligibility for the company'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.
• Support for professional growth through meaningful work and learning support.
• A 5-week fully paid sabbatical at the 5-year work anniversary.
• Premium app access for friends and family, plus health, pension and wellbeing perks.