Full Stack Engineer

Full Stack Software Engineer London (Hybrid: Tue-Thu in office, WFH Monday & Friday) Permanent £

Our client has built a comparison service for the UK wealth industry - it's live and working - and they're now expanding their tech stack considerably. They're hiring a mid-level developer to join the core build, working directly with the CTO.

They're looking for someone with the fundamentals to build on their stack who is a fanatic user of AI coding tools.

What you'll be doing

You'll work directly with the CTO on the platform behind everything they do. Day to day, that means:

• Designing, building and shipping features end-to-end across the platform

• Expanding the stack: new services, new integrations, and LLM-powered features built into the product itself

• Using AI development tools as standard practice - and helping shape how the team gets the most from them

• Contributing to architecture decisions as the platform scales

• Writing clean, well-tested code and reviewing others' work with care

• Debugging, profiling and improving performance, reliability and security What we're looking for

You'll need:

• The fundamentals to build on the client's tech stack - TypeScript, React/Next.js, Node, PostgreSQL and AWS

• Strong coding fundamentals - data structures, API design, testing, version control, and the judgement to know when to be rigorous and when to ship

• To be a fanatic user of AI coding tools: they're part of how you work every day, you follow the space closely, and you have opinions about what works

• Experience building with or integrating LLM APIs (Anthropic, OpenAI, etc.) - or personal projects that prove the interest is real

• The ability to thrive in a small team where you'll wear more than one hat

• Comfort being in the London office Tuesday to Thursday Nice to have:

• Experience in fintech, financial services or other regulated environments

• Familiarity with RAG pipelines, embeddings, prompt engineering or agentic frameworks

• Cloud platform experience (AWS/GCP/Azure), CI/CD, infrastructure-as-code

• Open-source contributions or a portfolio of side projects - especially AI-related

• Startup or scale-up experience What you'll get

• Direct mentorship from and daily collaboration with the CTO

• Real influence over technical direction - the platform is live, but the expansion is just beginning

• Budget for AI tools, hardware, and learning & development

• Hybrid working: Tuesday-Thursday in the London office, Monday and Friday from home

• 25 days holiday plus bank holidays

• Pension scheme Oscar Associates (UK) Limited is acting as an Employment Agency in relation to this vacancy.

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