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 to join the Runtime team at PolyAI. This team owns the core voice infrastructure that powers every call our AI agents handle - from the moment a phone rings to the moment it hangs up.
You'll work across the full real-time voice stack: telephony, real-time audio streaming and media handling, speech recognition and synthesis integration, LLM orchestration, turn-taking and voice activity detection, call recording, and the data pipeline that captures it all. We operate across AWS and Azure, serving enterprise customers at scale across multiple global regions.
What You'll Do:- Design and build features across the voice runtime - from new integrations with third-party contact centre platforms, to improving how our agents handle interruptions and overlapping speech, to scaling our infrastructure for higher call volumes.
- Own services end-to-end: write code, review PRs from across the company, deploy to production, and support what you ship.
- Debug complex, cross-service issues in production - the kind where a timing problem involves VAD thresholds, ASR transcription windows, LLM response latency, and audio playback all interacting at once.
- Contribute to architecture decisions and design documents. The team has strong thought leadership on stateful vs stateless service boundaries, API design, and where responsibilities should live.
- Collaborate with product facing teams who build on top of the runtime - helping them understand configuration, troubleshooting call behaviour, and unblocking their work.
- Improve the developer experience: better defaults, less reliance on opaque config, more features controllable through the UI, and better test coverage
Who we're looking for:
- 4+ years of commercial software development experience.
- Strong experience with real-time or latency-sensitive systems: streaming, media pipelines, networking, or similar domains where milliseconds matter.
- Solid understanding of distributed systems: gRPC, state management across services, connection error recovery, and working with systems that must not drop calls.
- Experience with cloud infrastructure on AWS (EKS/Kubernetes, Lambda, S3, DynamoDB, Redis) - comfortable deploying containerised services and debugging infrastructure-level issues.
- Strong written communication - design docs, PR reviews, and async debugging are core to how the team works.
Strong plus:
- Experience with speech technologies: ASR, TTS, VAD, or end-of-turn detection — either integrating them or working on the systems around them.
- Experience with Go - this is the primary language for our voice services. Most engineers on the team work across both Go and Python.
- Experience with Python - parts of our LLM orchestration layer, serverless function runtime, and data pipeline are Python.
- Prior work on LLM orchestration or agent frameworks: tool calling, function execution, prompt management, context window management, or conversation state machines.
- Experience with data pipeline technologies: Kafka, ClickHouse, S3-based event stores, or similar.
- Experience with observability at scale: Datadog, structured logging, SLO/SLI definition, and using metrics to drive reliability improvements.
- Multi-cloud experience (Azure in addition to AWS).
- Familiarity with VoIP/telephony (SIP, RTP) or WebRTC (STUN/TURN/ICE, media negotiation).
We offer competitive compensation based on experience, expertise, and the level of responsibility. This role also includes equity, giving you the opportunity to share in the long-term success of the business. The listed expectations reflect what we're hiring for, so we encourage you to review the job description carefully.
Benefits💰 Participation in the company’s employee share options plan
🏝 Tenure-Based PTO: You will receive 25 holidays when you join and will gain an additional 1 day after 2 years of service, then 1 day each year until capped at 32 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
🌎 Sabbatical Program: 5-week paid sabbatical available after 5 years of employment
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
We expect the best from our people, we hire people that expect the best from themselves, and we nurture this drive for excellence.
Ownership
We care deeply about what we do. We take ownership of our initiatives, decisions and outcomes.
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
Our world moves quickly and so do we. We take calculated risks and we deliver impact fast.
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
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.
