Senior Full Stack Engineer (Must be based in UK)

PolyAI automates customer service through lifelike voice assistants that let customers lead a conversation. Our voice assistants make it possible for businesses to deliver outstanding customer service that rivals their human agents. Our customers, which include the world’s leading logos, are expanding how they use our platform, driving automation of critical customer service operations and integrating PolyAI into their daily customer service workflows. PolyAI just raised our Series D from leading investors, such as Nvidia and Khosla Ventures, bringing our total funding to $200m. We serve enterprises where customer conversation is a critical part of doing business, partnering with leading companies such as Fedex, Marriott Hotels and Unicredit. Our AI agents have proven themselves to deliver significant customer value , at some enterprises doing the work of 1000+ FTEs. We're looking for a Senior Full Stack Engineer (with strong backend skills ) to join our product engineering team at a moment of exponential growth for our company. The Supervisor Suite team’s mission is to build best-in-class conversational intelligence, LLM-powered evaluation and data tools for PolyAI’s customer service agents. Our users are customer experience leaders, business analysts and contact center managers. We enable them to answer questions such as: How can we automate more of our business while increasing customer satisfaction? Did the voice agent respect our policies and procedures? What do our customers think about our offering? You might work on: LLM judges that evaluate our customer service AI agents for quality, safety and reliability at scale Smart Analyst , our flagship AI research agent for conversational data leveraging the latest agent harness and context engineering practices, to maximize insight per token Data pipelines that process millions of conversations daily and are at the foundation of PolyAI’s architecture Real-time dashboards and alerting systems providing observability of our AI agents You'll own features end-to-end, from collaborating on product direction and system design through to implementation and seeing real customers light up when they use what you've built. And because we're scaling fast, you'll get to experience what few engineers do: evolving your products and architecture in real-time as data volumes grow and customer needs expand. If you love building products that blend great UX with complex backend challenges, thrive in collaborative environments where engineers shape product decisions, and want to work on AI applications that are actually solving real business problems today, we'd love for you to join us! What You Will Do Full-Stack Development: Design and implement features end-to-end, using Python for backend services and React (Next.js preferred) for frontend interfaces. Create Intuitive Interfaces: Develop user-friendly UIs that simplify and visualise complex AI concepts. Champion Best Practices: Lead the team in adopting coding standards and best practices, ensuring a clean, maintainable, and scalable codebase. Collaborate: Work closely with cross-functional teams to design, develop, and deliver features that align with the platform’s vision. Mentor and Guide: Provide technical leadership and guidance to junior engineers, fostering a collaborative and growth-oriented environment. Optimise Performance: Improve backend workflows, streamline processes, and enhance overall system efficiency. What We Are Looking For Problem Solving: We are looking for people who enjoy diving into complex problems and possess high intellectual agility. Our team tackles novel challenges at the forefront of building AI agents, and is responsible for maintaining large-scale and critical services. 4+ YOE in software engineering with a track-record of delivering complex features end-to-end in a high-ownership environment. Proven Expertise in Python and SQL: Extensive experience building back ... (truncated, view full listing at source)