Lead Software Engineer | AI systems, backend, architecture | Fully remote, UK
£105,000 to £130,000. Permanent.
London. Fully remote across the UK.
You will own the engineering layer between AI capability and a product people can rely on. That means architecture, backend services, APIs and client applications, while staying close enough to the code to know where the real problems are.
Our client is an early-stage AI product company building applications that get on with everyday tasks before you ask. A prototype exists, launch is ahead, and the business is funded without depending on an upcoming round.
You’ll lead a small team of senior engineers and work closely with ML leadership. The remit crosses backend, mobile and desktop, and you need real depth in at least one of them.
The honest bit: this is leadership without much distance from delivery. You’ll review designs and code, make architectural calls with incomplete information, and still answer for it when latency, reliability or production behaviour goes wrong.
The job
Architecture. Set the application engineering direction across backend services, APIs and client platforms. Keep the architecture simple enough to move quickly, but coherent enough to scale.
AI product systems. Design the state, orchestration, tool use, retries, fallbacks and failure handling behind AI-powered workflows. You’ll build the abstractions that connect model capability to product behaviour.
Leadership. Lead a small senior engineering team through design reviews, code reviews and hands‑on mentorship. The job is to raise the standard of the engineering without replacing engineering with process.
Production. Set up observability, monitoring and testing, and the habits that keep them useful. You’ll make trade-offs across latency, reliability, cost, security and user experience, then measure whether those decisions hold up under real load.
What you’ll bring
Essential:
- Engineering teams you have led on complex application or product systems.
- Backend systems you have personally built and shipped to production.
- Architecture decisions you have owned across multiple services or clients.
- AI-powered products you have shipped using ML or LLM capabilities.
- Code review, design review and technical mentorship you still do yourself.
- Production systems where latency, reliability and observability mattered.
- Technical decisions you have made, and stood by, with incomplete information.
- Existing right to work in the UK.
Useful: mobile engineering, desktop applications, AI orchestration, distributed systems, production observability.
Who this suits
You are probably a Lead Software Engineer, Technical Lead or hands‑on Engineering Lead who still wants engineering responsibility, not just people management. You are comfortable moving between architecture, code and a senior team.
It won’t suit you if you want leading to mean leaving the code behind. Here you read the pull requests, make the architecture calls yourself and help trace the fault when production goes wrong.
Let’s talk
We welcome applicants from every background and will support reasonable adjustments.
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Lead Software Engineer in City of London employer: Xist4 IT Limited.
As a Frontend Engineer at our innovative company, you'll be part of a dynamic team dedicated to creating AI-native productivity applications that redefine everyday tasks. We offer a fully remote work environment, fostering a collaborative culture where your contributions directly impact product development. With opportunities for professional growth and the chance to work on complex, engaging projects, we are committed to supporting your career while ensuring a rewarding and meaningful work experience.
