Full Stack Engineer

Oscar Technology; Greater London; Hybrid; GBP 65,000 - 90,000; Full time

Benefits offered by this job

Mentorship with CTO

AI tool budget

Hybrid schedule

25 days holiday

Pension

Job summary

Oscar Technology in London is looking for a Full Stack Software Engineer to join a growing fintech-focused team. You will work with TypeScript, React/Next.js, Node, PostgreSQL and AWS to ship features end-to-end and build AI-enabled enhancements on a live platform.

You’ll collaborate closely with the CTO in a small team, shaping technical direction while delivering robust, scalable code in a hybrid setup (Tue-Thu in the office). The role includes mentoring and opportunities for growth.

Qualifications

• Fundamentals to build on the client's tech stack: TypeScript, React/Next.js, Node, PostgreSQL and AWS.
• Experience with AI coding tools and building with or integrating LLM APIs (Anthropic, OpenAI, etc.).
• Thrives in a small team where you’ll wear more than one hat and comfortable in London office Tue–Thu.

Responsibilities

• Designing, building and shipping features end-to-end across the platform.
• Expanding the stack with new services, integrations, and LLM-powered features.
• Using AI development tools as standard practice and shaping how the team uses them.
• Contributing to architecture decisions as the platform scales.
• Writing clean, well-tested code and reviewing others' work.
• Debugging, profiling and improving performance, reliability, and security.

Skills

TypeScript

React/Next.js

Node.js

PostgreSQL

AWS

Job description

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

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