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Senior Full Stack Engineer (Must be based in UK)

United Kingdom

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’re looking for talented Senior Full Stack Software Engineers to join one of our three high impact teams: Runtime, Data, and Product Engineering.

Responsibilities:

  • Architect and Develop: Design and implement our external-facing API that enables developers to build, manage, analyse, and interact with our agents. 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.
  • Create intuitive interfaces: Build user-friendly APIs and 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.

Requirements:

  • Proven Expertise in Python: 3+ years of extensive experience building backend systems, with a strong understanding of 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).
  • Agile Practitioner: Familiarity with Agile methodologies such as Scrum or Kanban.
  • Testing Advocate: Experience writing and maintaining unit tests in Python and JavaScript (Jest, React Testing Library, Playwright).
  • Security-Minded: Experience managing secure communication protocols between client and server.
  • Version Control: Proficiency with Git for collaborative development.
  • Additional Skills (Desirable): knowledge of Go and experience with Next.js

All three teams work closely together, share high engineering standards, and solve challenging technical problems at scale, but each has its own mission and area of focus.

  • Runtime: own the global infrastructure that powers real-time voice interactions. In this role, you’ll work at the core of the agentic process - streaming audio, transcribing speech, using LLMs and acting on their output, and synthesising natural voice. You’ll design and optimise systems across VoIP, WebRTC to deliver low-latency, secure, and reliable conversations. Your work directly shapes the user experience of every call, driving down response times, improving comprehension, and ensuring we meet strict SLAs for performance and security.
  • Data: play a key role in delivering the next generation of our no-code agent studio platform. In this role, you’ll be leading the design and development of features that power insight generation, reporting, and the data-driven backbone of our no-code platform for building voice assistants.
  • Product Engineering: help shape our cutting-edge low-code platform. This role offers the opportunity to work end-to-end, from design to implementation, on creating features which enable a simple user experience for interacting with complex AI systems.

We currently have multiple engineering roles open across different teams. Please apply to the one role that feels like the best match for your skills and experience.  Our Talent team will review your application against all open positions. If we believe you may be a stronger fit for another role or team, we’ll ensure your application is considered there as well.


Benefits

💰 Participation in the company’s employee share options plan

🏝 25 days holiday, plus bank holidays

🏡 Flexible working from home policy

🌎 Work from outside of the UK for up to 6 months each year

🫂TELUS Health EAP 24/7 - offers you and your chosen family confidential, judgment-free support for any work, health, or life challenge

🧡 Enhanced parental leave

🚲 Bike2Work scheme

📚 Annual learning and development allowance

🏡 We’re all about making WFH work for you - that’s why we offer a one-off WFH allowance when you join. Offering perks like noise-cancelling headphones or a comfortable desk chair to boost your comfort and focus!

👨‍👩‍👧 Company-funded fertility and family-forming programmes

🌸 Menopause care programme with Maven

🏥 Private healthcare and dental cover, discounts on gym members and relaxation apps, and access to a range of mental health programs


At PolyAI, we take great pride in our values - they guide everything we do. We believe that a strong culture leads to meaningful work and lasting impact.

Our core values are:

:only-the-best:
Only the best
We expect the best from our people, we hire people that expect the best from themselves, and we nurture this drive for excellence.

:ownership:
Ownership
We care deeply about what we do. We take ownership of our initiatives, decisions and outcomes.

:relentlessly-improve:
Relentlessly improve
We demand more from ourselves and are always evolving. Continuous, obsessive improvement is the only way we will transform the world of conversational AI.

:bias-for-action:
Bias for action
Our world moves quickly and so do we. We take calculated risks and we deliver impact fast.

:disagree-and-commit:
Disagree and commit
We are all working toward the same goal. If we donʼt agree with something, we work hard to understand it and when a decision is made, we accept it and give it our all.

:build-for-people:
Build for people
We want the world to enjoy the experiences they have with us. We are building for a future that prefers automation.


PolyAI is proud to be an equal-opportunity employer. We celebrate diversity and are committed to creating an inclusive environment for all employees. All employment decisions at PolyAI will be based on the business needs without attention to ethnicity, religion, sexual orientation, gender identity, family or parental status, national origin, neurodiversity status or disability status.


Kindly find the Privacy Notice for our recruitment process by following the link here. This document provides important information regarding how we handle your personal data throughout the recruitment journey.

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