Full-Stack Engineer (Data) in London

About us: Spectrum.Life is a whole-of-health digital partner that guides organisations and their people to thrive, delivering clinically backed digital health, mental health and wellbeing solutions. Our HealthTech delivers digital transformation for Insurers, Educators and Employers through Co-creation or seamlessly integrated out-of-the-box solutions, that decrease digital fragmentation and engage, empower, and transform their people's lives. Established in 2018, Spectrum.Life provides services internationally to over 7.2m insurance members, 3,000 corporate clients, 60 universities and 650,000 university students. Our vision is to change and save as many lives as possible.

Your profile: You are passionate about coding and continuously learning new technologies, especially in the rapidly evolving field of AI. You are a proactive problem-solver who takes ownership of your tasks from start to finish. You are a strategic thinker, excited by the prospect of defining the technical direction of a product. You have excellent communication skills and enjoy collaborating within a focused team. You are responsible, organized, and have a keen eye for detail. You are excited by the prospect of working in a role with significant impact and growth potential.

Role Brief: We are seeking a motivated and talented Full-Stack Engineer with a strong background in AI and backend systems to help architect and build the foundations of our AI Roadmap. In this role, you will have a unique opportunity to lead the technical design of critical AI-driven products that are set to provide a significant competitive advantage, positioning us as the gold standard in the AI mental health sector. You will join a dynamic team and take ownership of the core AI components that power our data ecosystem. If you are passionate about building robust AI-driven systems from the ground up, enjoy working across the technology stack, and are excited by the challenge of designing and implementing cutting-edge LLM solutions, this is the perfect role for you.

Responsibilities:

• Architectural Ownership & Design: Lead the technical design and architectural decisions for our core AI product. You will take ownership of the entire LLM lifecycle, from model selection and evaluation to deployment and monitoring, ensuring a clear and scalable design.
• LLM & Backend Engineering: Develop clean, secure, and performant serverless backend services using AWS Lambda and the wider AWS ecosystem. Design, build, and maintain the scaffolding for invoking Large Language Models (LLMs) via services like AWS Bedrock. Compare and evaluate different LLMs to determine the best fit for our use cases, establishing clear metrics and evaluation frameworks. Implement and manage robust data processing and storage solutions to support our AI features.
• Infrastructure & Best Practices: Design and deploy cloud infrastructure using modern best practices (e.g., Infrastructure as Code). Implement comprehensive testing, robust exception handling, and application monitoring to ensure the high availability and reliability of our AI services. Take charge of your local development environment and see features through to production, collaborating with the wider team to ensure seamless product integration. Champion and maintain high standards for code quality, scalability, and maintainability.

Requirements:

• Proven experience as a Full-Stack Engineer, with a strong portfolio of backend-focused or AI-driven projects.
• Expert proficiency in TypeScript and Node.js, with a deep understanding of modern JavaScript (ES6+), asynchronous programming patterns, and building scalable backend APIs and services.
• Extensive, hands-on experience architecting and building solutions on the AWS ecosystem, including core serverless services (Lambda, API Gateway, S3, EventBridge), databases (RDS, DynamoDB), security (IAM), and infrastructure as code tools (AWS CDK, CloudFormation, or Terraform).
• Strong experience in database design and management, with proficiency in both relational (e.g., PostgreSQL) and NoSQL databases.
• A solid understanding of Generative AI concepts and practical experience working with LLMs.
• Comfortable with the principles of LLM design, including prompt engineering and an understanding of model evaluation techniques.
• A solid understanding of the full software development lifecycle, including testing, monitoring, and deployment.

Plus:

• Experience with AWS Bedrock or similar LLM platforms.
• Familiarity with LLM evaluation tools like Langfuse.

Desirable: What are the benefits of working at Spectrum.Life? Full time permanent contract, competitive salary (Dependent on experience), in-office, remote or hybrid working options, 25 days annual leave, 24/7 EAP and a wide range of health and wellbeing supports, extensive list of employee perks and benefits.