Senior Engineer (ML Engineer)

Flo Health

500M+ downloads. 80M+ monthly users. A decade of building – and we’re still accelerating. Flo is the world’s #1 health & fitness app worldwide on a mission to build a better future for female health. Backed by a $200M investment led by General Atlantic, we became the first product of our kind to reach a $1B valuation in 2024 – and we’re not slowing down. With 7M paid subscribers and the highest-rated experience in the App Store’s health category, we’ve spent 10 years earning trust at scale. Now, we’re building the next generation of digital health – AI-powered, privacy-first, clinically backed – to help our users know their body better. The job We are looking for a Senior Software Engineer with deep expertise in AI/ML infrastructure to join our AI Platform team and help build the GenAI platform that powers every AI feature at Flo. You will bridge core infrastructure, data engineering, and LLM development to deliver production-grade medical safety judges, fine-tuning pipelines, evaluation frameworks, and real-time personalisation. The team operates 60+ LLM-based evaluation judges, develops proprietary fine-tuned health models, and maintains active partnerships with Databricks, Google, OpenAI, Anthropic, and AWS. What you’ll do * LLM Judge Ecosystem: build and scale Judge-as-a-Service, prompt registries, calibration pipelines, and evaluation orchestration using MLflow 3.x * Fine-Tuning and Serving: develop LoRA/SFT/preference optimisation pipelines for health-domain models (Llama, Gemma, MedGemma) and manage model serving at scale on Databricks * Data and Evaluation Pipelines: build synthetic Q&A generation, golden test sets, reward function engineering, and Delta table schemas in Unity Catalog for reliable, reproducible evaluation data * Infrastructure: maintain Terraform-managed AWS infrastructure (EKS, S3, IAM), Databricks AI Gateway, and CI/CD pipelines (GitHub Actions) with evaluation gates and progressive rollout * Cross-Functional Impact: collaborate with Product, Security, Analytics, and Medical teams, develop internal SDKs and APIs consumed by 5+ teams, and engage directly with technology partners on pre-release capabilities Experience and skills Must have: * Engineering maturity: 7+ years of software engineering, 4+ years focused on ML/AI platforms * LLM experience: recent hands-on work with at least one of: fine-tuning, prompt engineering, LLM evaluation, or model serving * Technical stack: strong Python across production services and data pipelines, data engineering fundamentals (Spark, Delta tables, Parquet) * Platform and infrastructure: Databricks (MLflow, Unity Catalog, Model Serving), AWS (EKS/Kubernetes, IAM), Terraform, GitHub Actions * Cross-domain flexibility: comfort working across ML, data engineering, and infrastructure. You don’t need to be expert in all three, but you contribute wherever the team needs it Nice to have: * LLM evaluation frameworks (judges, graders, calibration methodology) or fine-tuning techniques (LoRA, RLHF/DPO, model distillation) * ML data engineering: synthetic data generation, evaluation dataset design, annotation pipelines * Healthcare, regulated industry, or safety-critical AI systems experience * Prompt optimisation frameworks (DSPy or similar), feature stores (Tecton) #LI-KP1 #LI-Hybrid  Annual Salary Range (ranges may vary based on skills and experience) £120,000—£150,000 GBP How we work We’re a mission-led, product-driven team. We move fast, stay focused and take ownership – from brief to build to impact. Debate is encouraged. Decisions are shared. We care about craft, ship with purpose, and always raise the bar. You’ll be working with people who take their work seriously, not themselves. It takes commitment, resilience, and the drive to keep going when things get tough. Because better health outcomes are worth it.  What you'll get We support impact with meaningful reward. Here’s what that looks like: * 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 * In-person collaboration and work in a hybrid model, with 3 days per week spent in the office * 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 – nothing else. We’re proud to be an equal opportunity employer, and we welcome applicants from all backgrounds, communities and identities. Read our privacy notice for job applicants.

Epicgames

WHAT MAKES US EPIC? At the core of Epic’s success are talented, passionate people. Epic prides itself on creating a collaborative, welcoming, and creative environment. Whether it’s building award-winning games or crafting engine technology that enables others to make visually stunning interactive experiences, we’re always innovating. Being Epic means being a part of a team that continually strives to do right by our community and users. We’re constantly innovating to raise the bar of engine and game development. ENGINEERING - GAMES WHAT WE DO Unreal projects have been leading the pack of real-time entertainment with our constantly growing team of engineering experts. We’re always improving on the tools and technology that empower content developers worldwide. WHAT YOU'LL DO You will work with our team of engineers at the intersection of vision, language and machine learning to create state-of-the-art models for agentic vision tools. You will be responsible for the design, implementation and deployment of production-ready computer vision models that support game developers in our ecosystem (including scene generation and trained bots/agents), as well as agents for automated content verification (e.g. gameplay behavior). IN THIS ROLE, YOU WILL * Create and deliver production-ready, scalable and high-quality deep-learning models and associated algorithms for computer vision problems * Critically assess the effectiveness of such models and make recommendations for the ongoing roadmap * Methodically understand and assess the effectiveness of new data channels and support collection/creation of new ones WHAT WE'RE LOOKING FOR * PhD in Computer Science, Mathematics or related field, 5+ years of relevant industry experience * Proven track record creating innovative solutions for problems in Computer Vision and deploying them as production-level systems in industrial environments * Expert, hands-on knowledge of: * Deep learning techniques for supervised, semi-supervised and unsupervised learning * Reinforcement learning, imitation learning, and related frameworks * Python and associated ML tools/frameworks (numpy, scipy, sklearn, pytorch)  * Experience with working collaboratively with other developers, following a flexible/agile/lean approach * Desirable: * Experience with architecting, scaling, securing and operating ML systems in the cloud (ideally AWS) at medium to large scale * Experience with 3D Vision/Graphics EPIC JOB + EPIC BENEFITS = EPIC LIFE We pay 100% for benefits except for PMI (for dependents). Our current benefits package includes pension, private medical insurance, health care cash plan, dental insurance, disability and life insurance, critical illness, cycle to work scheme, flu shots, health checks, and meals. We also offer a robust mental well-being program through Modern Health, which provides free therapy and coaching for employees & dependents. ABOUT US Epic Games is a leading interactive entertainment company. For over 30 years we've been making award-winning games and engine technology that empowers others to make visually stunning games and 3D content that bring environments to life like never before. Epic's award-winning Unreal Engine technology not only provides game developers the ability to build high-fidelity, interactive experiences for PC, console, mobile, and VR, it is also a tool being embraced by content creators across a variety of industries such as media and entertainment, automotive, and architectural design. As we continue to build our Engine technology and develop remarkable games, we strive to build teams of world-class talent. LIKE WHAT YOU HEAR? COME BE A PART OF SOMETHING EPIC! Epic Games deeply values diverse teams and an inclusive work culture, and we are proud to be an Equal Opportunity employer. Learn more about our Equal Employment Opportunity (EEO) Policy here. Note to Recruitment Agencies: Epic does not accept any unsolicited resumes or approaches from any unauthorized third party (including recruitment or placement agencies) (i.e., a third party with whom we do not have a negotiated and validly executed agreement). We will not pay any fees to any unauthorized third party. Further details on these matters can be found here.

Graphcore

ABOUT THE JOB Help prove the ML software stack that future AI systems will depend on. Graphcore is expanding the software systems behind AI compute at datacenter scale. This role focuses on validating a complex machine learning stack before it reaches customers and hardware.You will build the test infrastructure, automation and tooling that engineers trust every day. Your work will help raise reliability, performance and maintainability across frameworks, simulators, emulators and future hardware. You will shape test architecture across large codebases, CI pipelines and representative ML workloads. You will use strong software engineering judgement to turn complex technical goals into scalable validation systems. This is a role for someone who enjoys depth, ownership and useful engineering. You will make quality easier, faster and more visible for teams building at the edge of AI compute. THE TEAM AND CULTURE The ML QA team sits where Graphcore’s software components come together. Engineers work across unit tests, integration tests, full model runs, subgraph validation and benchmarking. Work is organised through focused squads with clear ownership. People are expected to step up, speak openly and improve how the team builds, tests and learns. Decisions are grounded in evidence from code, data and system behaviour. The team works closely with software teams to identify gaps, improve tooling and move priorities forward quickly. WHAT WE’RE LOOKING FOR · Strong software design skills, with experience building maintainable systems across large codebases. · Production Python experience, including testable, reliable code used by other engineers. · Experience with CI/CD, automated testing and Linux based development workflows. · Familiarity with C or C++, with confidence reading and debugging low level code. · Understanding of ML frameworks, workloads or model execution beyond simple API usage. · Ability to mentor engineers, improve practices and take ownership of complex technical problems. BENEFITS · Unlimited annual leave · Up to 5% matched pension · Phantom equity – share in Graphcore’s success · True flexibility in how and where you work · Office spaces designed for collaboration · Free food and an on-site barista · Health cash plan · Income protection · Life assurance · Along with other benefits you can choose from (private medical insurance, dental plan etc) We welcome people from all backgrounds and experiences and are committed to building an inclusive environment where everyone can do their best work. We’re an equal opportunity employer and recognise that everyone brings different strengths and perspectives. If you need any adjustments during the interview process, just let us know - we’re happy to support you. JOIN THE TEAM AT GRAPHCORE Graphcore is one of the world’s leading innovators in Artificial Intelligence compute. It is developing hardware, software and systems infrastructure that will unlock the next generation of AI breakthroughs and power the widespread adoption of AI solutions across every industry. As part of the SoftBank Group, Graphcore is a member of an elite family of companies responsible for some of the world’s most transformative technologies. Together, they share a bold vision: to enable Artificial Super Intelligence and ensure its benefits are accessible to everyone. Graphcore’s teams are drawn from diverse backgrounds and bring a broad range of skills and perspectives. A melting pot of AI research specialists, silicon designers, software engineers and systems architects, Graphcore brings together deep expertise to solve complex problems and deliver meaningful progress in AI compute. If you want to shape how complex ML software is tested, trusted and improved, we’d love to hear from you. Apply now to be part of the journey.