Senior AI Software Engineer

London (Hybrid, 3 days per week) Up to £140,000 + Equity

We're partnered with a fast-growing AI start-up building cutting-edge behavioural intelligence technology for the financial services sector. Backed by an exceptional leadership team and industry experts, they're developing a platform that helps organisations better understand client behaviour through advanced AI and large language models.

As their first senior individual contributor engineering hire, you'll play a critical role in shaping both the product and engineering culture from the ground up.

The Opportunity This is a true 0-to-1 product engineering role. You'll work closely with senior leadership to build and scale a greenfield product, taking ownership across the full stack while driving the architecture and evolution of production-grade AI systems. You'll have significant influence over technical direction, engineering standards, product decisions and future hiring as the team grows.

What You'll Be Doing Building and shipping customer-facing product features end-to-end Developing and scaling production LLM applications Owning RAG pipelines and AI application architecture Implementing guardrails, evaluations, caching and model routing strategies Working across TypeScript, React, Node.js, PostgreSQL and AWS (Open to different technology backgrounds!) Building API-first services for enterprise customers Establishing engineering best practices around testing, deployment and code quality Collaborating directly with product and leadership stakeholders to influence roadmap and delivery priorities

What We're Looking For Experience building and scaling production LLM-powered applications Strong full-stack engineering background Experience delivering secure, reliable and scalable systems Comfortable working across multiple technologies and learning new stacks quickly Experience with React and modern web applications Product-minded approach with the ability to operate autonomously Passion for building in an early-stage, high-growth environment Experience within regulated industries or financial services is beneficial but not essential

Why Join? Up to £140,000 base salary Meaningful equity package Opportunity to become the first senior engineering hire Direct impact on architecture, product and company direction Work alongside talent from leading technology and AI organisations Greenfield product with genuine product ownership Hybrid working in Central London 25 days holiday plus additional benefit