Lead Software Engineer

Understanding Recruitment; Greater London; Hybrid; GBP 90,000 - 140,000; Full time

Job summary

Understanding Recruitment is partnering with a fast-growing AI startup in London seeking a Lead Software Engineer. You will own technical direction, architect scalable backend systems, and lead a small team.

You will work on agentic AI workflows and real-time AI infrastructure while delivering robust, scalable solutions. The role demands 5-8+ years of hands-on software engineering, a strong CS/engineering/math background, and deep expertise in Node.js, NestJS, REST APIs, and microservices.

Qualifications

• Degree in Computer Science, Engineering or Mathematics from a strong university.
• 5-8+ years of hands-on software engineering experience.
• Expertise in Node.js and NestJS.
• Strong experience building RESTful APIs and microservices.

Responsibilities

• Architect scalable backend systems and APIs end-to-end.
• Design microservice and event-driven architectures for real-time AI workflows.
• Build infrastructure powering AI agents at scale.
• Lead a small team of engineers and set engineering standards.

Skills

Node.js

NestJS

REST APIs

Microservices

Agentic AI

Leadership

TypeScript

Education

Computer Science degree

Engineering degree

Mathematics degree

Tools

Claude Code

Google Cloud

MongoDB

Qdrant

React

Next.js

TypeScript

Job description

Are you a hands‑on engineer ready to take real ownership of architecture, engineering standards and a small team in a fast‑moving AI startup?

Are you excited by agentic AI, building from scratch, and having a genuine impact on both the technology and product?

Lead Software Engineer – AI Startup

Location: London (4 days a week)

Experience: 5-8+ years (startup, AI, SaaS or automation experience preferred)

I’m excited to be working with a rapidly growing AI startup building an AI system of action for the UK property industry. Their technology sits on top of estate and letting agents’ existing systems, using AI to automate operational work including prospecting, viewings, maintenance, compliance and arrears.

At the heart of the platform is an AI voice agent that acts as a 24/7 front desk, answering calls and emails, qualifying leads, booking viewings and triaging maintenance enquiries, with their technology already being used by agencies across the UK.

They’re now looking for a Lead Software Engineer to work closely with the Head of Engineering and founders, owning technical direction while remaining highly hands‑on.

This is an opportunity for someone who wants to build the hardest things, set the technical standard and lead from the front.

You’ll work directly on:

• Architecting and building scalable backend systems and APIs end-to-end
• Designing microservice and event‑driven architectures supporting real‑time AI workflows
• Building the infrastructure that powers agentic AI at scale
• Leading a small team of engineers, driving delivery and reviewing their work
• Setting the standard for how the team uses AI coding tools and agentic workflows
• Building secure, performant and maintainable systems as the platform scales

They’re particularly interested in engineers who have:

• A Computer Science, Engineering, Mathematics or related degree from a strong university
• 5-8+ years of strong hands‑on software engineering experience
• Deep expertise in Node.js and NestJS
• Strong experience building RESTful APIs and microservice‑based systems
• Experience with LLMs, AI agents and agentic workflows
• Experience using tools such as Claude Code as part of your everyday development workflow
• Previously owned technical direction on significant projects
• A strong background in startups, AI, SaaS or automation platforms
• Strong product instinct and willingness to get close to customers
• Node.js / NestJS
• React / Next.js
• TypeScript
• Google Cloud
• MongoDB
• Qdrant
• Microservices & event‑driven architecture
• LLMs, AI agents & agentic development workflows

What they’re looking for:

• Exceptional engineer first – you want to build, not just manage
• High ownership – comfortable making decisions without layers of approval
• AI‑native mindset – you’re already experimenting with how agents can make engineers faster and better
• Strong technical judgement – you know when to build, when not to build, and how to build for scale
• Natural leadership – you can bring engineers with you while maintaining a high technical bar
• Startup mentality – hungry, pragmatic and comfortable with ambiguity
• Genuine technical ownership from day one
• Lead a small, high‑calibre engineering team
• Help define how an AI‑native engineering organisation operates
• Build technology solving a real, high‑value problem for UK property businesses
• Huge scope to influence architecture, product and engineering culture

If you’re a hands‑on engineer who wants to own hard technical problems, lead from the front and help define what agentic engineering looks like in a high‑growth AI startup, this could be a very exciting next move.