Senior Applied AI Engineer at numan

About Numan  Founded in 2018, we’ve already grown to be a 300+ team distributed across the globe, united by a singular mission: empowering people to take control of their health. Numan is transforming health: we’ve built a cutting-edge platform that integrates diagnostics, medication, supplements, digital programmes, and doctor consultations. Giving people the tools they need to maximise life. To deliver on our transformative mission, we are guided by our 5 company values:  • Patients first. • Learn fast. • Own the quality. • Succeed together. • Care deeply. Backed by top-tier investors, Numan is already having a positive impact on hundreds of thousands of patients here in the UK, and we want you to help us deliver this mission! The role We are looking for a backend-focused AI Systems Engineer to join our growing team. We are a fast-moving, agile team of experienced engineers who take pride in delivering high-quality work. You will play a key role in building the AI platform that powers the next generation of Numan products, with direct responsibility for shaping how AI capabilities are designed, deployed and scaled across the company. You’ll be: • Designing and building LLM-powered agents and orchestration workflows. • Building and maintaining robust evaluation pipelines for prompts, agents and conversation quality. • Developing retrieval-augmented generation architectures, retrieval pipelines and long-term memory integrations. • Implementing observability, tracing and debugging tooling to monitor AI system behaviour and maintain production health. • Building backend services and APIs to enable AI capabilities across multiple products. • Improving reliability, latency, cost efficiency and scalability of LLM workloads in production environments. • Collaborating closely with Product, Engineering and Clinical stakeholders to define requirements and shape technical approaches for AI-driven capabilities. • Establishing best practices across prompt versioning, evaluation pipelines, experiment tracking and testing frameworks. • Contributing to AI platform architecture, CI/CD and deployment pipelines. • Supporting and mentoring colleagues, helping to strengthen applied AI and backend engineering capability across the team. We’re looking for someone who: • Is motivated to build AI systems that deliver meaningful, positive impact in healthcare. • Has a demonstrated track record of taking AI-powered features from prototype through to production deployment. • Has strong backend engineering experience, preferably in Python, including designing scalable APIs, distributed systems, asynchronous processing and working with Docker and CI/CD pipelines. • Has hands-on experience building LLM-powered applications, including familiarity with agent frameworks such as LangChain, LangGraph or similar, and designing retrieval-augmented generation pipelines at scale. • Brings a systems-oriented and reliability-focused approach, with experience designing end-to-end AI architectures and working with observability, logging and production monitoring tools. • Has experience evaluating model outputs and running structured experiments to improve system performance. • Is comfortable working across the full development lifecycle, from architecture decisions through deployment and monitoring. It’s a bonus if you have: • Built or contributed to multi-agent systems. • Worked with LLM evaluation frameworks and dataset-driven testing approaches. • An understanding of safety systems, guardrails and policy enforcement mechanisms. • Led or supported prompt lifecycle management and versioning at scale. • Used vector databases such as pgvector, Qdrant or Pinecone. • Exposure to fine-tuning or model adaptation workflows. Our benefits include... 📈  -  Share options. 🏖  -  25 days holiday, plus bank holidays (increasing to 30 the longer you stay with Numan).  🩺  -  Health insurance with Vitality. 🧸  -  Enhanced maternity and parental leave.  🐥  -  Nursery benefit provided by YellowNest. 💼  -  Employee assistance programme (access to therapy, financial planning and discounts). ⚖️  -  Generous pension (includes both employee and employer contributions). 💻  -  Flexible working options, including a dog-friendly office in Farringdon.  📚  -  Personal training and development budget via Learnerbly.  👟  -  Wellhub membership, giving you access to over 2,000 locations in the UK.  🚲  -  Cycle to work scheme. 🚆  -  Season ticket loan.  %   -  Discount on Numan products for your friends and family. 🤲  -  Paid volunteering days.  📅  -  An additional 2 weeks off once you reach your 5th anniversary with Numan. Diversity at Numan At Numan, people are at the heart of who we are. We recognise and value the unique perspectives and experiences that individuals from all backgrounds bring. We promote innovation and creativity, enabling us to tackle things from various viewpoints and are committed to equal opportunities and continuously strive to create a workplace where everyone feels respected, heard, and valued. Embracing diversity isn't just our goal; it's our strength, driving us towards a more inclusive future.