Senior Software Engineer (Must be based in UK)

Entrepreneur First; United Kingdom; Hybrid; GBP 125,000 - 150,000; Full time

Job summary

A conversational AI firm is seeking a Senior Software Engineer based in the United Kingdom. This role involves building reliable APIs, deploying advanced speech models, and contributing to infrastructure development. Candidates should have over 3 years of experience in engineering, strong Python skills, and the ability to design and maintain RESTful APIs. Competitive compensation and flexible working options are offered.

Benefits

Competitive compensation with equity

Flexible work from home policy

Private healthcare and dental cover

Annual learning and development allowance

Company-funded fertility and family-forming programmes

Qualifications

• 3+ years of programming experience in a software engineering role.
• Hands-on experience in designing, deploying, and maintaining RESTful APIs.
• Proficient in software engineering best practices.

Responsibilities

• Building reliable APIs for interacting with Voice Agent deployments.
• Deploying state-of-the-art speech-to-text and text-to-speech models.
• Contributing to multi-tenant infrastructure implementation.

Skills

Python

RESTful APIs

Software engineering best practices

Algorithms and data structures

English communication

Education

Bachelor’s or Master’s in Computer Science or relevant field

Job description

Overview

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 a Senior Software Engineer based in the United Kingdom to join one of our high impact teams: Runtime, Data, and Product Engineering. All three teams maintain high engineering standards, solve challenging technical problems at scale, and collaborate closely to deliver value.

Responsibilities

• Building reliable APIs for interacting with the runtime of our Voice Agent deployments.
• Deploying state-of-the-art speech-to-text, LLMs and text-to-speech models.
• Taking a major role in software development, including writing code, tests, contributing to design ideas and documents, and performing code reviews.
• Contributing to the implementation of our multi-tenant infrastructure.

Requirements

• 3+ years of programming experience in a software engineering role, with strong proficiency in Python.
• Hands-on experience in designing, deploying, and maintaining RESTful APIs.
• Experience with professional software engineering best practices, such as coding standards, code reviews, source control, build processes, and testing.
• Understanding of algorithms, data structures, system design and complexity analysis.
• Bachelor’s degree or Master’s in Computer Science, Engineering, a relevant technical field or equivalent practical experience.
• Proficiency in verbal and written English communication.

Team focus

• Runtime: Own the global infrastructure that powers real-time voice interactions. 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 and WebRTC to deliver low-latency, secure, and reliable conversations, shaping the user experience of every call and meeting strict performance and security SLAs.
• Data: Play a key role in delivering the next generation of our no-code agent studio platform, leading design and development of features for insight generation, reporting, and the data-driven backbone of our platform.
• Product Engineering: Help shape our cutting-edge low-code platform, working end-to-end to create features that enable a simple user experience for interacting with complex AI systems.

Benefits & Perks

• Competitive compensation based on experience, with equity opportunities.
• Participation in the company’s employee share options plan.
• Flexible working from home policy and a one-off WFH allowance at joining.
• Ability to work from outside the UK for up to 6 months per year.
• Private healthcare and dental cover, gym discounts, and access to mental health programs.
• Annual learning and development allowance.
• Company-funded fertility and family-forming programmes.

Value and culture

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 business needs without regard to ethnicity, religion, sexual orientation, gender identity, family or parental status, national origin, neurodiversity status or disability status.

Our core values are: Only the best, Ownership, Relentlessly improve, Bias for action, Disagree and commit, Build for people. We are focused on meaningful work and lasting impact in the field of conversational AI.

Application guidance

We currently have multiple engineering roles open across different teams. Please apply to the one role that best matches your skills and experience. Our Talent team will review applications and may consider you for other roles where appropriate.