Fullstack Engineer

La Fosse Associates; Greater London; Hybrid; GBP 86,000 - 105,000; Full time

Job summary

La Fosse Associates is seeking a Senior Full Stack Software Engineer to own a production SaaS platform and help shape product strategy in a London hybrid setting. You will design and scale full-stack apps using TypeScript, React, Next.js, Go and Python on AWS, while building AI-powered features and AI tooling for enterprise customers.

The role focuses on delivering production software, improving platform reliability, and collaborating with founders to guide engineering direction as the business

Qualifications

• Strong commercial experience as a Software Engineer or Senior Software Engineer.
• Expertise with TypeScript, React, Next.js and modern web app development.
• Experience building and operating cloud platforms using AWS.
• Strong SQL and database design experience.
• Experience delivering production software products.
• Experience building AI features using LLM APIs and AI tooling.

Responsibilities

• Own a production, multi-tenant SaaS platform for enterprise clients.
• Design, build and scale full-stack applications using TS, React, Next.js, Go, Python, AWS.
• Build AI-powered features, LLM integrations and agentic workflows.
• Work directly with founders to influence product strategy and engineering direction.
• Develop cloud-native systems using AWS Serverless, Lambda, PostgreSQL and APIs.
• Improve reliability, observability, security, performance and scalability.

Skills

TypeScript

React

Next.js

AWS

SQL

PostgreSQL

AI

LLMs

OpenAI

Vercel

Tools

Supabase

CI/CD

Serverless

Job description

Senior Full Stack Software Engineer (TypeScript, React, Next.js, AI, AWS) | Up to £95,000 + Equity | London Hybrid

I’m partnered with a high-growth deep-tech scale-up spun out of Imperial College London that’s helping accelerate the future of electrification. Backed by leading investors, they’ve built a battery software platform already used by global automotive, aviation, and industrial customers, with a Series A on the horizon and ambitious growth plans.

They’re now looking for a Senior Full Stack Software Engineer to take ownership of their production SaaS platform, build the next generation of AI-powered capabilities, and work directly with the founders to shape both the product and engineering function as the business scales.

The Role

• Own a production, multi-tenant SaaS platform used by enterprise customers.
• Design, build and scale full-stack applications using TypeScript, React, Next.js, Go, Python and AWS.
• Build AI-powered features, LLM integrations, agentic workflows and automation tools.
• Work directly with founders to influence product strategy, engineering direction and future hiring.
• Develop cloud-native systems using AWS Serverless, Lambda, PostgreSQL, Supabase and modern API architectures.
• Improve platform reliability, observability, security, performance and scalability.
• Support CI/CD, Infrastructure as Code and software engineering best practices.

Tech Stack

TypeScript, React, Next.js, Node.js, Go, Python, AWS, Lambda, PostgreSQL, SQL, Supabase, API Development, AI, Machine Learning, LLMs, OpenAI, Claude, MCP, RAG, Serverless, CI/CD, Infrastructure as Code

What They’re Looking For

• Strong commercial experience as a Software Engineer, Full Stack Engineer, Full Stack Developer or Senior Software Engineer.
• Expertise with TypeScript, React, Next.js and modern web application development.
• Experience building and operating cloud platforms using AWS.
• Strong SQL, PostgreSQL and database design experience.
• Demonstrable experience delivering production software products.
• Experience building AI features using LLM APIs, prompt engineering, agentic workflows or AI tooling.
• Comfortable operating in a fast-moving startup or scale-up environment.

Nice To Have

• Node.js and Go experience.
• Experience with Supabase and Vercel.
• RAG, MCP, AI Agents, Evaluation Frameworks and AI Product Development.
• Python, Pandas and data tooling experience.
• Startup, scale-up or founding engineer experience.
• Interest in ClimateTech, EnergyTech, Scientific Software or Battery Technology.