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. PolyAI just raised our Series D from leading investors such as Nvidia and Khosla Ventures, bringing our total funding to $200m. We serve enterprises like 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.

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.

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
• Data pipelines that process millions of conversations daily
• 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.

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
• Collaborate cross-functionally
• Mentor and Guide junior engineers
• Optimise Performance of backend workflows

What We Are Looking For

• 4+ YOE in software engineering with a track-record of delivering complex features end-to-end
• Proven Expertise in Python and SQL, REST APIs
• Experience with designing data schemas, building and maintaining data pipelines/ETLs (event-driven processing is a plus)
• Frontend Confidence: Strong experience with React and JavaScript (TypeScript preferred); experience with Tailwind
• Testing: Experience writing and maintaining unit tests in Python and JavaScript (Jest)
• Proficiency with Git

Desirable: Knowledge of Golang, Next.js, production-grade systems incorporating LLMs