Lead Platform Engineer

Lead Platform Engineer
Central London (4 days on site) · Full-time, permanent

About the company
A fast-growing, venture-backed AI start-up building an AI system of action for the UK property sector. The platform sits on top of the customer’s CRM and runs their day-to-day operational work: prospecting, viewings, maintenance, compliance and arrears. Much of that work runs through a real-time voice agent that answers the phone when the branch can’t.

The role
We’re looking for a Lead Platform Engineer to work under the Head of Engineering and own the build across the stack. You’ll be a great engineer first: the person who builds the hardest things and sets the technical standard.

Agentic AI runs through the heart of the business. The team works in an agentic engineering environment, where developers use Claude Code and AI agents every day, and the product itself is built on agentic pipelines. We expect you to be ahead of the team on this, setting the bar for how we build with AI and constantly raising the standard of quality and features.

What you’ll do

• Architect, design and build scalable backend systems and APIs across the stack, end to end, from architecture through to production.
• Design and maintain microservice and event-driven architectures that support the voice agent’s real-time operational workflows.
• Lead a small team of engineers: drive their delivery, review their work, and be accountable for what ships.
• Set the standard for how the team builds with agentic AI, from Claude Code workflows to the patterns everyone adopts.
• Contribute to technical strategy and architecture decisions, working directly with the Head of Engineering on what gets built, how it gets built, and what doesn’t get built yet.
• Maintain secure, performant and maintainable systems, and reliable data pipelines, as the platform scales across customers.
• Get close to the product: understand the property workflows the platform automates, so the systems you build solve the right problems.

Who you are

1. 5–8+ years of hands-on software engineering experience, ideally in AI, SaaS or automation platforms.
2. A first-class or strong degree in Computer Science, Engineering, Mathematics or a related field.
3. Already a lead engineer, or very close to it. You’ve owned the technical direction of real projects and you’re ready to own more.
4. Deep expertise in Node.js and NestJS, with strong experience designing and building RESTful APIs and microservice-based systems. Frontend and Next.js experience is ideal too.
5. A real focus on agentic AI. You’ve built with LLMs and agents, you understand what breaks in agentic pipelines at scale, and you use Claude Code and agentic workflows as a matter of course, not as novelties.
6. You come from a start-up, or you were a standout performer at a top firm. You’ve worked in a small, fast-paced team where you had to make the right call without a committee, and you performed.
7. Hungry. You’d rather own a hard problem with a small team than have a comfortable seat in a big organisation.
8. You can lead engineers and bring them with you, while still being the strongest builder in the room.

This role isn’t for you if

• You prefer a 9–5 role in a large firm with established playbooks and little ownership.
• You want a pure people-management track with no hands on the keyboard.
• You treat AI coding tools as optional extras.
• You need months of ramp-up time before you can contribute.

This is a from-scratch environment where the standard is set by whoever shows up. You’ll be expected to both build and lead from day one.

The stack

• NestJS backend and Next.js frontend
• A monorepo deployed as microservices
• Hosted on Google Cloud and Kubernetes
• Data stored in Postgres, MongoDB and Qdrant

Everything is built to run agents, not just respond to them.

What good looks like

• Month 1: You know the stack deeply, you’ve shipped something meaningful, and the Head of Engineering trusts your technical judgement.
• Month 3: You own a major part of the system, you’re leading a small team on it, and you’ve introduced at least one agentic practice that makes the whole team faster.
• Month 6: You’re the go-to person for the hardest engineering problems, your team ships reliably, and you’ve set the agentic development standard.
• Month 12: The platform scales to every UK agency that needs it, and a meaningful part of that, in both architecture and people, is yours.