Senior Full Stack Engineer (Hybrid - Manhattan based 1-2x week)

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. We are seeking an experienced Senior Full Stack Developer (backend-focused) to join our team and shape our cutting-edge low-code platform. In this role, you’ll work end to end, from design to implementation, building systems that make it easy for users to interact with complex AI. This team will be our first product engineering team in New York, and you would be the first Senior Engineer within it. Accordingly you will play a foundational role in setting engineering standards, making key architectural decisions, and defining the technical direction of the platform. We’re looking for engineers who are comfortable operating as senior technical decision-makers and taking accountability for system-wide architectural choices. You’ll own user journeys and core infrastructure, mentor others, and influence engineering strategy across the team. If you’re passionate about Python and great API design, or love working with React to build intuitive tools that empower non-technical users to harness AI, we’d love to hear from you! Your responsibilities will involve: Architect and Develop: Own and evolve the architectural direction of our external-facing API that enables developers to build, manage, analyse, and interact with our agents. Take a key role in the design of scalable, maintainable systems and make high-impact decisions around performance and reliability. Help to build and enhance our no-code platform, enabling non-technical users to configure sophisticated dialogue systems and voice experiences. Full Stack Development: Design and implement features end-to-end, using Python for backend services and React (Next.js preferred) for frontend interfaces. Take responsibility not just for delivery, but for ensuring solutions align with long term architectural vision. Create Intuitive Interfaces: Build user-friendly APIs and UIs that simplify and visualise complex AI concepts, balancing technical depth with usability for diverse end users. Champion Best Practices: Lead the team in adopting coding standards and engineering best practices. Drive improvements in code quality, testing, documentation, and infrastructure to ensure a clean, maintainable, and scalable codebase. Technical Leadership Decision Making: Operate autonomously in ambiguous environments, making thoughtful technical trade-offs that balance speed, quality, and scalability. Act as a senior technical voice in cross-functional discussions and influence technical strategy in the team. Mentor and Guide: Provide technical leadership and mentorship to junior engineers, fostering a collaborative and growth-oriented environment, and elevate the overall engineering bar within the team. Optimise Performance: Improve backend workflows, streamline processes, and enhance overall system efficiency. Requirements: Proven Backend Expertise: 5+ years of experience building backend systems (Python preferred), with a strong understanding of REST and non-REST APIs (experience with WebSockets is a plus). Frontend Proficiency: Strong experience with React and JavaScript (TypeScript preferred); experience with CSS-in-JS and utility-first CSS frameworks (e.g., styled-components, Tailwind CSS). Architectural Ownership: Experience leading technical initiatives or large projects, defining system design, owning production systems end to end, and making thoughtful architectural trade offs to ensure long term maintainability and scalability in high growth or evolving environments. Product Builder: Understanding of how to build for diverse end ... (truncated, view full listing at source)